+++ /dev/null
-QEMU Coding Style
-=================
-
-Please use the script checkpatch.pl in the scripts directory to check
-patches before submitting.
-
-1. Whitespace
-
-Of course, the most important aspect in any coding style is whitespace.
-Crusty old coders who have trouble spotting the glasses on their noses
-can tell the difference between a tab and eight spaces from a distance
-of approximately fifteen parsecs. Many a flamewar has been fought and
-lost on this issue.
-
-QEMU indents are four spaces. Tabs are never used, except in Makefiles
-where they have been irreversibly coded into the syntax.
-Spaces of course are superior to tabs because:
-
- - You have just one way to specify whitespace, not two. Ambiguity breeds
- mistakes.
- - The confusion surrounding 'use tabs to indent, spaces to justify' is gone.
- - Tab indents push your code to the right, making your screen seriously
- unbalanced.
- - Tabs will be rendered incorrectly on editors who are misconfigured not
- to use tab stops of eight positions.
- - Tabs are rendered badly in patches, causing off-by-one errors in almost
- every line.
- - It is the QEMU coding style.
-
-Do not leave whitespace dangling off the ends of lines.
-
-1.1 Multiline Indent
-
-There are several places where indent is necessary:
-
- - if/else
- - while/for
- - function definition & call
-
-When breaking up a long line to fit within line width, we need a proper indent
-for the following lines.
-
-In case of if/else, while/for, align the secondary lines just after the
-opening parenthesis of the first.
-
-For example:
-
- if (a == 1 &&
- b == 2) {
-
- while (a == 1 &&
- b == 2) {
-
-In case of function, there are several variants:
-
- * 4 spaces indent from the beginning
- * align the secondary lines just after the opening parenthesis of the
- first
-
-For example:
-
- do_something(x, y,
- z);
-
- do_something(x, y,
- z);
-
- do_something(x, do_another(y,
- z));
-
-2. Line width
-
-Lines should be 80 characters; try not to make them longer.
-
-Sometimes it is hard to do, especially when dealing with QEMU subsystems
-that use long function or symbol names. Even in that case, do not make
-lines much longer than 80 characters.
-
-Rationale:
- - Some people like to tile their 24" screens with a 6x4 matrix of 80x24
- xterms and use vi in all of them. The best way to punish them is to
- let them keep doing it.
- - Code and especially patches is much more readable if limited to a sane
- line length. Eighty is traditional.
- - The four-space indentation makes the most common excuse ("But look
- at all that white space on the left!") moot.
- - It is the QEMU coding style.
-
-3. Naming
-
-Variables are lower_case_with_underscores; easy to type and read. Structured
-type names are in CamelCase; harder to type but standing out. Enum type
-names and function type names should also be in CamelCase. Scalar type
-names are lower_case_with_underscores_ending_with_a_t, like the POSIX
-uint64_t and family. Note that this last convention contradicts POSIX
-and is therefore likely to be changed.
-
-When wrapping standard library functions, use the prefix qemu_ to alert
-readers that they are seeing a wrapped version; otherwise avoid this prefix.
-
-4. Block structure
-
-Every indented statement is braced; even if the block contains just one
-statement. The opening brace is on the line that contains the control
-flow statement that introduces the new block; the closing brace is on the
-same line as the else keyword, or on a line by itself if there is no else
-keyword. Example:
-
- if (a == 5) {
- printf("a was 5.\n");
- } else if (a == 6) {
- printf("a was 6.\n");
- } else {
- printf("a was something else entirely.\n");
- }
-
-Note that 'else if' is considered a single statement; otherwise a long if/
-else if/else if/.../else sequence would need an indent for every else
-statement.
-
-An exception is the opening brace for a function; for reasons of tradition
-and clarity it comes on a line by itself:
-
- void a_function(void)
- {
- do_something();
- }
-
-Rationale: a consistent (except for functions...) bracing style reduces
-ambiguity and avoids needless churn when lines are added or removed.
-Furthermore, it is the QEMU coding style.
-
-5. Declarations
-
-Mixed declarations (interleaving statements and declarations within
-blocks) are generally not allowed; declarations should be at the beginning
-of blocks.
-
-Every now and then, an exception is made for declarations inside a
-#ifdef or #ifndef block: if the code looks nicer, such declarations can
-be placed at the top of the block even if there are statements above.
-On the other hand, however, it's often best to move that #ifdef/#ifndef
-block to a separate function altogether.
-
-6. Conditional statements
-
-When comparing a variable for (in)equality with a constant, list the
-constant on the right, as in:
-
- if (a == 1) {
- /* Reads like: "If a equals 1" */
- do_something();
- }
-
-Rationale: Yoda conditions (as in 'if (1 == a)') are awkward to read.
-Besides, good compilers already warn users when '==' is mis-typed as '=',
-even when the constant is on the right.
-
-7. Comment style
-
-We use traditional C-style /* */ comments and avoid // comments.
-
-Rationale: The // form is valid in C99, so this is purely a matter of
-consistency of style. The checkpatch script will warn you about this.
-
-Multiline comment blocks should have a row of stars on the left,
-and the initial /* and terminating */ both on their own lines:
- /*
- * like
- * this
- */
-This is the same format required by the Linux kernel coding style.
-
-(Some of the existing comments in the codebase use the GNU Coding
-Standards form which does not have stars on the left, or other
-variations; avoid these when writing new comments, but don't worry
-about converting to the preferred form unless you're editing that
-comment anyway.)
-
-Rationale: Consistency, and ease of visually picking out a multiline
-comment from the surrounding code.
-
-8. trace-events style
-
-8.1 0x prefix
-
-In trace-events files, use a '0x' prefix to specify hex numbers, as in:
-
-some_trace(unsigned x, uint64_t y) "x 0x%x y 0x" PRIx64
-
-An exception is made for groups of numbers that are hexadecimal by
-convention and separated by the symbols '.', '/', ':', or ' ' (such as
-PCI bus id):
-
-another_trace(int cssid, int ssid, int dev_num) "bus id: %x.%x.%04x"
-
-However, you can use '0x' for such groups if you want. Anyway, be sure that
-it is obvious that numbers are in hex, ex.:
-
-data_dump(uint8_t c1, uint8_t c2, uint8_t c3) "bytes (in hex): %02x %02x %02x"
-
-Rationale: hex numbers are hard to read in logs when there is no 0x prefix,
-especially when (occasionally) the representation doesn't contain any letters
-and especially in one line with other decimal numbers. Number groups are allowed
-to not use '0x' because for some things notations like %x.%x.%x are used not
-only in Qemu. Also dumping raw data bytes with '0x' is less readable.
-
-8.2 '#' printf flag
-
-Do not use printf flag '#', like '%#x'.
-
-Rationale: there are two ways to add a '0x' prefix to printed number: '0x%...'
-and '%#...'. For consistency the only one way should be used. Arguments for
-'0x%' are:
- - it is more popular
- - '%#' omits the 0x for the value 0 which makes output inconsistent
--- /dev/null
+=================
+QEMU Coding Style
+=================
+
+.. contents:: Table of Contents
+
+Please use the script checkpatch.pl in the scripts directory to check
+patches before submitting.
+
+Whitespace
+==========
+
+Of course, the most important aspect in any coding style is whitespace.
+Crusty old coders who have trouble spotting the glasses on their noses
+can tell the difference between a tab and eight spaces from a distance
+of approximately fifteen parsecs. Many a flamewar has been fought and
+lost on this issue.
+
+QEMU indents are four spaces. Tabs are never used, except in Makefiles
+where they have been irreversibly coded into the syntax.
+Spaces of course are superior to tabs because:
+
+* You have just one way to specify whitespace, not two. Ambiguity breeds
+ mistakes.
+* The confusion surrounding 'use tabs to indent, spaces to justify' is gone.
+* Tab indents push your code to the right, making your screen seriously
+ unbalanced.
+* Tabs will be rendered incorrectly on editors who are misconfigured not
+ to use tab stops of eight positions.
+* Tabs are rendered badly in patches, causing off-by-one errors in almost
+ every line.
+* It is the QEMU coding style.
+
+Do not leave whitespace dangling off the ends of lines.
+
+Multiline Indent
+----------------
+
+There are several places where indent is necessary:
+
+* if/else
+* while/for
+* function definition & call
+
+When breaking up a long line to fit within line width, we need a proper indent
+for the following lines.
+
+In case of if/else, while/for, align the secondary lines just after the
+opening parenthesis of the first.
+
+For example:
+
+.. code-block:: c
+
+ if (a == 1 &&
+ b == 2) {
+
+ while (a == 1 &&
+ b == 2) {
+
+In case of function, there are several variants:
+
+* 4 spaces indent from the beginning
+* align the secondary lines just after the opening parenthesis of the first
+
+For example:
+
+.. code-block:: c
+
+ do_something(x, y,
+ z);
+
+ do_something(x, y,
+ z);
+
+ do_something(x, do_another(y,
+ z));
+
+Line width
+==========
+
+Lines should be 80 characters; try not to make them longer.
+
+Sometimes it is hard to do, especially when dealing with QEMU subsystems
+that use long function or symbol names. Even in that case, do not make
+lines much longer than 80 characters.
+
+Rationale:
+
+* Some people like to tile their 24" screens with a 6x4 matrix of 80x24
+ xterms and use vi in all of them. The best way to punish them is to
+ let them keep doing it.
+* Code and especially patches is much more readable if limited to a sane
+ line length. Eighty is traditional.
+* The four-space indentation makes the most common excuse ("But look
+ at all that white space on the left!") moot.
+* It is the QEMU coding style.
+
+Naming
+======
+
+Variables are lower_case_with_underscores; easy to type and read. Structured
+type names are in CamelCase; harder to type but standing out. Enum type
+names and function type names should also be in CamelCase. Scalar type
+names are lower_case_with_underscores_ending_with_a_t, like the POSIX
+uint64_t and family. Note that this last convention contradicts POSIX
+and is therefore likely to be changed.
+
+When wrapping standard library functions, use the prefix ``qemu_`` to alert
+readers that they are seeing a wrapped version; otherwise avoid this prefix.
+
+Block structure
+===============
+
+Every indented statement is braced; even if the block contains just one
+statement. The opening brace is on the line that contains the control
+flow statement that introduces the new block; the closing brace is on the
+same line as the else keyword, or on a line by itself if there is no else
+keyword. Example:
+
+.. code-block:: c
+
+ if (a == 5) {
+ printf("a was 5.\n");
+ } else if (a == 6) {
+ printf("a was 6.\n");
+ } else {
+ printf("a was something else entirely.\n");
+ }
+
+Note that 'else if' is considered a single statement; otherwise a long if/
+else if/else if/.../else sequence would need an indent for every else
+statement.
+
+An exception is the opening brace for a function; for reasons of tradition
+and clarity it comes on a line by itself:
+
+.. code-block:: c
+
+ void a_function(void)
+ {
+ do_something();
+ }
+
+Rationale: a consistent (except for functions...) bracing style reduces
+ambiguity and avoids needless churn when lines are added or removed.
+Furthermore, it is the QEMU coding style.
+
+Declarations
+============
+
+Mixed declarations (interleaving statements and declarations within
+blocks) are generally not allowed; declarations should be at the beginning
+of blocks.
+
+Every now and then, an exception is made for declarations inside a
+#ifdef or #ifndef block: if the code looks nicer, such declarations can
+be placed at the top of the block even if there are statements above.
+On the other hand, however, it's often best to move that #ifdef/#ifndef
+block to a separate function altogether.
+
+Conditional statements
+======================
+
+When comparing a variable for (in)equality with a constant, list the
+constant on the right, as in:
+
+.. code-block:: c
+
+ if (a == 1) {
+ /* Reads like: "If a equals 1" */
+ do_something();
+ }
+
+Rationale: Yoda conditions (as in 'if (1 == a)') are awkward to read.
+Besides, good compilers already warn users when '==' is mis-typed as '=',
+even when the constant is on the right.
+
+Comment style
+=============
+
+We use traditional C-style /``*`` ``*``/ comments and avoid // comments.
+
+Rationale: The // form is valid in C99, so this is purely a matter of
+consistency of style. The checkpatch script will warn you about this.
+
+Multiline comment blocks should have a row of stars on the left,
+and the initial /``*`` and terminating ``*``/ both on their own lines:
+
+.. code-block:: c
+
+ /*
+ * like
+ * this
+ */
+
+This is the same format required by the Linux kernel coding style.
+
+(Some of the existing comments in the codebase use the GNU Coding
+Standards form which does not have stars on the left, or other
+variations; avoid these when writing new comments, but don't worry
+about converting to the preferred form unless you're editing that
+comment anyway.)
+
+Rationale: Consistency, and ease of visually picking out a multiline
+comment from the surrounding code.
+
+trace-events style
+==================
+
+0x prefix
+---------
+
+In trace-events files, use a '0x' prefix to specify hex numbers, as in:
+
+.. code-block::
+
+ some_trace(unsigned x, uint64_t y) "x 0x%x y 0x" PRIx64
+
+An exception is made for groups of numbers that are hexadecimal by
+convention and separated by the symbols '.', '/', ':', or ' ' (such as
+PCI bus id):
+
+.. code-block::
+
+ another_trace(int cssid, int ssid, int dev_num) "bus id: %x.%x.%04x"
+
+However, you can use '0x' for such groups if you want. Anyway, be sure that
+it is obvious that numbers are in hex, ex.:
+
+.. code-block::
+
+ data_dump(uint8_t c1, uint8_t c2, uint8_t c3) "bytes (in hex): %02x %02x %02x"
+
+Rationale: hex numbers are hard to read in logs when there is no 0x prefix,
+especially when (occasionally) the representation doesn't contain any letters
+and especially in one line with other decimal numbers. Number groups are allowed
+to not use '0x' because for some things notations like %x.%x.%x are used not
+only in Qemu. Also dumping raw data bytes with '0x' is less readable.
+
+'#' printf flag
+---------------
+
+Do not use printf flag '#', like '%#x'.
+
+Rationale: there are two ways to add a '0x' prefix to printed number: '0x%...'
+and '%#...'. For consistency the only one way should be used. Arguments for
+'0x%' are:
+
+* it is more popular
+* '%#' omits the 0x for the value 0 which makes output inconsistent
+++ /dev/null
-1. Preprocessor
-
-1.1. Variadic macros
-
-For variadic macros, stick with this C99-like syntax:
-
-#define DPRINTF(fmt, ...) \
- do { printf("IRQ: " fmt, ## __VA_ARGS__); } while (0)
-
-1.2. Include directives
-
-Order include directives as follows:
-
-#include "qemu/osdep.h" /* Always first... */
-#include <...> /* then system headers... */
-#include "..." /* and finally QEMU headers. */
-
-The "qemu/osdep.h" header contains preprocessor macros that affect the behavior
-of core system headers like <stdint.h>. It must be the first include so that
-core system headers included by external libraries get the preprocessor macros
-that QEMU depends on.
-
-Do not include "qemu/osdep.h" from header files since the .c file will have
-already included it.
-
-2. C types
-
-It should be common sense to use the right type, but we have collected
-a few useful guidelines here.
-
-2.1. Scalars
-
-If you're using "int" or "long", odds are good that there's a better type.
-If a variable is counting something, it should be declared with an
-unsigned type.
-
-If it's host memory-size related, size_t should be a good choice (use
-ssize_t only if required). Guest RAM memory offsets must use ram_addr_t,
-but only for RAM, it may not cover whole guest address space.
-
-If it's file-size related, use off_t.
-If it's file-offset related (i.e., signed), use off_t.
-If it's just counting small numbers use "unsigned int";
-(on all but oddball embedded systems, you can assume that that
-type is at least four bytes wide).
-
-In the event that you require a specific width, use a standard type
-like int32_t, uint32_t, uint64_t, etc. The specific types are
-mandatory for VMState fields.
-
-Don't use Linux kernel internal types like u32, __u32 or __le32.
-
-Use hwaddr for guest physical addresses except pcibus_t
-for PCI addresses. In addition, ram_addr_t is a QEMU internal address
-space that maps guest RAM physical addresses into an intermediate
-address space that can map to host virtual address spaces. Generally
-speaking, the size of guest memory can always fit into ram_addr_t but
-it would not be correct to store an actual guest physical address in a
-ram_addr_t.
-
-For CPU virtual addresses there are several possible types.
-vaddr is the best type to use to hold a CPU virtual address in
-target-independent code. It is guaranteed to be large enough to hold a
-virtual address for any target, and it does not change size from target
-to target. It is always unsigned.
-target_ulong is a type the size of a virtual address on the CPU; this means
-it may be 32 or 64 bits depending on which target is being built. It should
-therefore be used only in target-specific code, and in some
-performance-critical built-per-target core code such as the TLB code.
-There is also a signed version, target_long.
-abi_ulong is for the *-user targets, and represents a type the size of
-'void *' in that target's ABI. (This may not be the same as the size of a
-full CPU virtual address in the case of target ABIs which use 32 bit pointers
-on 64 bit CPUs, like sparc32plus.) Definitions of structures that must match
-the target's ABI must use this type for anything that on the target is defined
-to be an 'unsigned long' or a pointer type.
-There is also a signed version, abi_long.
-
-Of course, take all of the above with a grain of salt. If you're about
-to use some system interface that requires a type like size_t, pid_t or
-off_t, use matching types for any corresponding variables.
-
-Also, if you try to use e.g., "unsigned int" as a type, and that
-conflicts with the signedness of a related variable, sometimes
-it's best just to use the *wrong* type, if "pulling the thread"
-and fixing all related variables would be too invasive.
-
-Finally, while using descriptive types is important, be careful not to
-go overboard. If whatever you're doing causes warnings, or requires
-casts, then reconsider or ask for help.
-
-2.2. Pointers
-
-Ensure that all of your pointers are "const-correct".
-Unless a pointer is used to modify the pointed-to storage,
-give it the "const" attribute. That way, the reader knows
-up-front that this is a read-only pointer. Perhaps more
-importantly, if we're diligent about this, when you see a non-const
-pointer, you're guaranteed that it is used to modify the storage
-it points to, or it is aliased to another pointer that is.
-
-2.3. Typedefs
-
-Typedefs are used to eliminate the redundant 'struct' keyword, since type
-names have a different style than other identifiers ("CamelCase" versus
-"snake_case"). Each named struct type should have a CamelCase name and a
-corresponding typedef.
-
-Since certain C compilers choke on duplicated typedefs, you should avoid
-them and declare a typedef only in one header file. For common types,
-you can use "include/qemu/typedefs.h" for example. However, as a matter
-of convenience it is also perfectly fine to use forward struct
-definitions instead of typedefs in headers and function prototypes; this
-avoids problems with duplicated typedefs and reduces the need to include
-headers from other headers.
-
-2.4. Reserved namespaces in C and POSIX
-Underscore capital, double underscore, and underscore 't' suffixes should be
-avoided.
-
-3. Low level memory management
-
-Use of the malloc/free/realloc/calloc/valloc/memalign/posix_memalign
-APIs is not allowed in the QEMU codebase. Instead of these routines,
-use the GLib memory allocation routines g_malloc/g_malloc0/g_new/
-g_new0/g_realloc/g_free or QEMU's qemu_memalign/qemu_blockalign/qemu_vfree
-APIs.
-
-Please note that g_malloc will exit on allocation failure, so there
-is no need to test for failure (as you would have to with malloc).
-Calling g_malloc with a zero size is valid and will return NULL.
-
-Prefer g_new(T, n) instead of g_malloc(sizeof(T) * n) for the following
-reasons:
-
- a. It catches multiplication overflowing size_t;
- b. It returns T * instead of void *, letting compiler catch more type
- errors.
-
-Declarations like T *v = g_malloc(sizeof(*v)) are acceptable, though.
-
-Memory allocated by qemu_memalign or qemu_blockalign must be freed with
-qemu_vfree, since breaking this will cause problems on Win32.
-
-4. String manipulation
-
-Do not use the strncpy function. As mentioned in the man page, it does *not*
-guarantee a NULL-terminated buffer, which makes it extremely dangerous to use.
-It also zeros trailing destination bytes out to the specified length. Instead,
-use this similar function when possible, but note its different signature:
-void pstrcpy(char *dest, int dest_buf_size, const char *src)
-
-Don't use strcat because it can't check for buffer overflows, but:
-char *pstrcat(char *buf, int buf_size, const char *s)
-
-The same limitation exists with sprintf and vsprintf, so use snprintf and
-vsnprintf.
-
-QEMU provides other useful string functions:
-int strstart(const char *str, const char *val, const char **ptr)
-int stristart(const char *str, const char *val, const char **ptr)
-int qemu_strnlen(const char *s, int max_len)
-
-There are also replacement character processing macros for isxyz and toxyz,
-so instead of e.g. isalnum you should use qemu_isalnum.
-
-Because of the memory management rules, you must use g_strdup/g_strndup
-instead of plain strdup/strndup.
-
-5. Printf-style functions
-
-Whenever you add a new printf-style function, i.e., one with a format
-string argument and following "..." in its prototype, be sure to use
-gcc's printf attribute directive in the prototype.
-
-This makes it so gcc's -Wformat and -Wformat-security options can do
-their jobs and cross-check format strings with the number and types
-of arguments.
-
-6. C standard, implementation defined and undefined behaviors
-
-C code in QEMU should be written to the C99 language specification. A copy
-of the final version of the C99 standard with corrigenda TC1, TC2, and TC3
-included, formatted as a draft, can be downloaded from:
- http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf
-
-The C language specification defines regions of undefined behavior and
-implementation defined behavior (to give compiler authors enough leeway to
-produce better code). In general, code in QEMU should follow the language
-specification and avoid both undefined and implementation defined
-constructs. ("It works fine on the gcc I tested it with" is not a valid
-argument...) However there are a few areas where we allow ourselves to
-assume certain behaviors because in practice all the platforms we care about
-behave in the same way and writing strictly conformant code would be
-painful. These are:
- * you may assume that integers are 2s complement representation
- * you may assume that right shift of a signed integer duplicates
- the sign bit (ie it is an arithmetic shift, not a logical shift)
-
-In addition, QEMU assumes that the compiler does not use the latitude
-given in C99 and C11 to treat aspects of signed '<<' as undefined, as
-documented in the GNU Compiler Collection manual starting at version 4.0.
-
-7. Error handling and reporting
-
-7.1 Reporting errors to the human user
-
-Do not use printf(), fprintf() or monitor_printf(). Instead, use
-error_report() or error_vreport() from error-report.h. This ensures the
-error is reported in the right place (current monitor or stderr), and in
-a uniform format.
-
-Use error_printf() & friends to print additional information.
-
-error_report() prints the current location. In certain common cases
-like command line parsing, the current location is tracked
-automatically. To manipulate it manually, use the loc_*() from
-error-report.h.
-
-7.2 Propagating errors
-
-An error can't always be reported to the user right where it's detected,
-but often needs to be propagated up the call chain to a place that can
-handle it. This can be done in various ways.
-
-The most flexible one is Error objects. See error.h for usage
-information.
-
-Use the simplest suitable method to communicate success / failure to
-callers. Stick to common methods: non-negative on success / -1 on
-error, non-negative / -errno, non-null / null, or Error objects.
-
-Example: when a function returns a non-null pointer on success, and it
-can fail only in one way (as far as the caller is concerned), returning
-null on failure is just fine, and certainly simpler and a lot easier on
-the eyes than propagating an Error object through an Error ** parameter.
-
-Example: when a function's callers need to report details on failure
-only the function really knows, use Error **, and set suitable errors.
-
-Do not report an error to the user when you're also returning an error
-for somebody else to handle. Leave the reporting to the place that
-consumes the error returned.
-
-7.3 Handling errors
-
-Calling exit() is fine when handling configuration errors during
-startup. It's problematic during normal operation. In particular,
-monitor commands should never exit().
-
-Do not call exit() or abort() to handle an error that can be triggered
-by the guest (e.g., some unimplemented corner case in guest code
-translation or device emulation). Guests should not be able to
-terminate QEMU.
-
-Note that &error_fatal is just another way to exit(1), and &error_abort
-is just another way to abort().
--- /dev/null
+============
+QEMU Hacking
+============
+
+.. contents:: Table of Contents
+
+Preprocessor
+============
+
+Variadic macros
+---------------
+
+For variadic macros, stick with this C99-like syntax:
+
+.. code-block:: c
+
+ #define DPRINTF(fmt, ...) \
+ do { printf("IRQ: " fmt, ## __VA_ARGS__); } while (0)
+
+Include directives
+------------------
+
+Order include directives as follows:
+
+.. code-block:: c
+
+ #include "qemu/osdep.h" /* Always first... */
+ #include <...> /* then system headers... */
+ #include "..." /* and finally QEMU headers. */
+
+The "qemu/osdep.h" header contains preprocessor macros that affect the behavior
+of core system headers like <stdint.h>. It must be the first include so that
+core system headers included by external libraries get the preprocessor macros
+that QEMU depends on.
+
+Do not include "qemu/osdep.h" from header files since the .c file will have
+already included it.
+
+C types
+=======
+
+It should be common sense to use the right type, but we have collected
+a few useful guidelines here.
+
+Scalars
+-------
+
+If you're using "int" or "long", odds are good that there's a better type.
+If a variable is counting something, it should be declared with an
+unsigned type.
+
+If it's host memory-size related, size_t should be a good choice (use
+ssize_t only if required). Guest RAM memory offsets must use ram_addr_t,
+but only for RAM, it may not cover whole guest address space.
+
+If it's file-size related, use off_t.
+If it's file-offset related (i.e., signed), use off_t.
+If it's just counting small numbers use "unsigned int";
+(on all but oddball embedded systems, you can assume that that
+type is at least four bytes wide).
+
+In the event that you require a specific width, use a standard type
+like int32_t, uint32_t, uint64_t, etc. The specific types are
+mandatory for VMState fields.
+
+Don't use Linux kernel internal types like u32, __u32 or __le32.
+
+Use hwaddr for guest physical addresses except pcibus_t
+for PCI addresses. In addition, ram_addr_t is a QEMU internal address
+space that maps guest RAM physical addresses into an intermediate
+address space that can map to host virtual address spaces. Generally
+speaking, the size of guest memory can always fit into ram_addr_t but
+it would not be correct to store an actual guest physical address in a
+ram_addr_t.
+
+For CPU virtual addresses there are several possible types.
+vaddr is the best type to use to hold a CPU virtual address in
+target-independent code. It is guaranteed to be large enough to hold a
+virtual address for any target, and it does not change size from target
+to target. It is always unsigned.
+target_ulong is a type the size of a virtual address on the CPU; this means
+it may be 32 or 64 bits depending on which target is being built. It should
+therefore be used only in target-specific code, and in some
+performance-critical built-per-target core code such as the TLB code.
+There is also a signed version, target_long.
+abi_ulong is for the ``*``-user targets, and represents a type the size of
+'void ``*``' in that target's ABI. (This may not be the same as the size of a
+full CPU virtual address in the case of target ABIs which use 32 bit pointers
+on 64 bit CPUs, like sparc32plus.) Definitions of structures that must match
+the target's ABI must use this type for anything that on the target is defined
+to be an 'unsigned long' or a pointer type.
+There is also a signed version, abi_long.
+
+Of course, take all of the above with a grain of salt. If you're about
+to use some system interface that requires a type like size_t, pid_t or
+off_t, use matching types for any corresponding variables.
+
+Also, if you try to use e.g., "unsigned int" as a type, and that
+conflicts with the signedness of a related variable, sometimes
+it's best just to use the *wrong* type, if "pulling the thread"
+and fixing all related variables would be too invasive.
+
+Finally, while using descriptive types is important, be careful not to
+go overboard. If whatever you're doing causes warnings, or requires
+casts, then reconsider or ask for help.
+
+Pointers
+--------
+
+Ensure that all of your pointers are "const-correct".
+Unless a pointer is used to modify the pointed-to storage,
+give it the "const" attribute. That way, the reader knows
+up-front that this is a read-only pointer. Perhaps more
+importantly, if we're diligent about this, when you see a non-const
+pointer, you're guaranteed that it is used to modify the storage
+it points to, or it is aliased to another pointer that is.
+
+Typedefs
+--------
+
+Typedefs are used to eliminate the redundant 'struct' keyword, since type
+names have a different style than other identifiers ("CamelCase" versus
+"snake_case"). Each named struct type should have a CamelCase name and a
+corresponding typedef.
+
+Since certain C compilers choke on duplicated typedefs, you should avoid
+them and declare a typedef only in one header file. For common types,
+you can use "include/qemu/typedefs.h" for example. However, as a matter
+of convenience it is also perfectly fine to use forward struct
+definitions instead of typedefs in headers and function prototypes; this
+avoids problems with duplicated typedefs and reduces the need to include
+headers from other headers.
+
+Reserved namespaces in C and POSIX
+----------------------------------
+
+Underscore capital, double underscore, and underscore 't' suffixes should be
+avoided.
+
+Low level memory management
+===========================
+
+Use of the malloc/free/realloc/calloc/valloc/memalign/posix_memalign
+APIs is not allowed in the QEMU codebase. Instead of these routines,
+use the GLib memory allocation routines g_malloc/g_malloc0/g_new/
+g_new0/g_realloc/g_free or QEMU's qemu_memalign/qemu_blockalign/qemu_vfree
+APIs.
+
+Please note that g_malloc will exit on allocation failure, so there
+is no need to test for failure (as you would have to with malloc).
+Calling g_malloc with a zero size is valid and will return NULL.
+
+Prefer g_new(T, n) instead of g_malloc(sizeof(T) ``*`` n) for the following
+reasons:
+
+* It catches multiplication overflowing size_t;
+* It returns T ``*`` instead of void ``*``, letting compiler catch more type errors.
+
+Declarations like
+
+.. code-block:: c
+
+ T *v = g_malloc(sizeof(*v))
+
+are acceptable, though.
+
+Memory allocated by qemu_memalign or qemu_blockalign must be freed with
+qemu_vfree, since breaking this will cause problems on Win32.
+
+String manipulation
+===================
+
+Do not use the strncpy function. As mentioned in the man page, it does *not*
+guarantee a NULL-terminated buffer, which makes it extremely dangerous to use.
+It also zeros trailing destination bytes out to the specified length. Instead,
+use this similar function when possible, but note its different signature:
+
+.. code-block:: c
+
+ void pstrcpy(char *dest, int dest_buf_size, const char *src)
+
+Don't use strcat because it can't check for buffer overflows, but:
+
+.. code-block:: c
+
+ char *pstrcat(char *buf, int buf_size, const char *s)
+
+The same limitation exists with sprintf and vsprintf, so use snprintf and
+vsnprintf.
+
+QEMU provides other useful string functions:
+
+.. code-block:: c
+
+ int strstart(const char *str, const char *val, const char **ptr)
+ int stristart(const char *str, const char *val, const char **ptr)
+ int qemu_strnlen(const char *s, int max_len)
+
+There are also replacement character processing macros for isxyz and toxyz,
+so instead of e.g. isalnum you should use qemu_isalnum.
+
+Because of the memory management rules, you must use g_strdup/g_strndup
+instead of plain strdup/strndup.
+
+Printf-style functions
+======================
+
+Whenever you add a new printf-style function, i.e., one with a format
+string argument and following "..." in its prototype, be sure to use
+gcc's printf attribute directive in the prototype.
+
+This makes it so gcc's -Wformat and -Wformat-security options can do
+their jobs and cross-check format strings with the number and types
+of arguments.
+
+C standard, implementation defined and undefined behaviors
+==========================================================
+
+C code in QEMU should be written to the C99 language specification. A copy
+of the final version of the C99 standard with corrigenda TC1, TC2, and TC3
+included, formatted as a draft, can be downloaded from:
+
+ `<http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf>`_
+
+The C language specification defines regions of undefined behavior and
+implementation defined behavior (to give compiler authors enough leeway to
+produce better code). In general, code in QEMU should follow the language
+specification and avoid both undefined and implementation defined
+constructs. ("It works fine on the gcc I tested it with" is not a valid
+argument...) However there are a few areas where we allow ourselves to
+assume certain behaviors because in practice all the platforms we care about
+behave in the same way and writing strictly conformant code would be
+painful. These are:
+
+* you may assume that integers are 2s complement representation
+* you may assume that right shift of a signed integer duplicates
+ the sign bit (ie it is an arithmetic shift, not a logical shift)
+
+In addition, QEMU assumes that the compiler does not use the latitude
+given in C99 and C11 to treat aspects of signed '<<' as undefined, as
+documented in the GNU Compiler Collection manual starting at version 4.0.
+
+Error handling and reporting
+============================
+
+Reporting errors to the human user
+----------------------------------
+
+Do not use printf(), fprintf() or monitor_printf(). Instead, use
+error_report() or error_vreport() from error-report.h. This ensures the
+error is reported in the right place (current monitor or stderr), and in
+a uniform format.
+
+Use error_printf() & friends to print additional information.
+
+error_report() prints the current location. In certain common cases
+like command line parsing, the current location is tracked
+automatically. To manipulate it manually, use the loc_``*``() from
+error-report.h.
+
+Propagating errors
+------------------
+
+An error can't always be reported to the user right where it's detected,
+but often needs to be propagated up the call chain to a place that can
+handle it. This can be done in various ways.
+
+The most flexible one is Error objects. See error.h for usage
+information.
+
+Use the simplest suitable method to communicate success / failure to
+callers. Stick to common methods: non-negative on success / -1 on
+error, non-negative / -errno, non-null / null, or Error objects.
+
+Example: when a function returns a non-null pointer on success, and it
+can fail only in one way (as far as the caller is concerned), returning
+null on failure is just fine, and certainly simpler and a lot easier on
+the eyes than propagating an Error object through an Error ``*````*`` parameter.
+
+Example: when a function's callers need to report details on failure
+only the function really knows, use Error ``*````*``, and set suitable errors.
+
+Do not report an error to the user when you're also returning an error
+for somebody else to handle. Leave the reporting to the place that
+consumes the error returned.
+
+Handling errors
+---------------
+
+Calling exit() is fine when handling configuration errors during
+startup. It's problematic during normal operation. In particular,
+monitor commands should never exit().
+
+Do not call exit() or abort() to handle an error that can be triggered
+by the guest (e.g., some unimplemented corner case in guest code
+translation or device emulation). Guests should not be able to
+terminate QEMU.
+
+Note that &error_fatal is just another way to exit(1), and &error_abort
+is just another way to abort().
+++ /dev/null
- QEMU README
- ===========
-
-QEMU is a generic and open source machine & userspace emulator and
-virtualizer.
-
-QEMU is capable of emulating a complete machine in software without any
-need for hardware virtualization support. By using dynamic translation,
-it achieves very good performance. QEMU can also integrate with the Xen
-and KVM hypervisors to provide emulated hardware while allowing the
-hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
-near native performance for CPUs. When QEMU emulates CPUs directly it is
-capable of running operating systems made for one machine (e.g. an ARMv7
-board) on a different machine (e.g. an x86_64 PC board).
-
-QEMU is also capable of providing userspace API virtualization for Linux
-and BSD kernel interfaces. This allows binaries compiled against one
-architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
-different architecture ABI (e.g. the Linux x86_64 ABI). This does not
-involve any hardware emulation, simply CPU and syscall emulation.
-
-QEMU aims to fit into a variety of use cases. It can be invoked directly
-by users wishing to have full control over its behaviour and settings.
-It also aims to facilitate integration into higher level management
-layers, by providing a stable command line interface and monitor API.
-It is commonly invoked indirectly via the libvirt library when using
-open source applications such as oVirt, OpenStack and virt-manager.
-
-QEMU as a whole is released under the GNU General Public License,
-version 2. For full licensing details, consult the LICENSE file.
-
-
-Building
-========
-
-QEMU is multi-platform software intended to be buildable on all modern
-Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
-of other UNIX targets. The simple steps to build QEMU are:
-
- mkdir build
- cd build
- ../configure
- make
-
-Additional information can also be found online via the QEMU website:
-
- https://qemu.org/Hosts/Linux
- https://qemu.org/Hosts/Mac
- https://qemu.org/Hosts/W32
-
-
-Submitting patches
-==================
-
-The QEMU source code is maintained under the GIT version control system.
-
- git clone https://git.qemu.org/git/qemu.git
-
-When submitting patches, one common approach is to use 'git
-format-patch' and/or 'git send-email' to format & send the mail to the
-qemu-devel@nongnu.org mailing list. All patches submitted must contain
-a 'Signed-off-by' line from the author. Patches should follow the
-guidelines set out in the HACKING and CODING_STYLE files.
-
-Additional information on submitting patches can be found online via
-the QEMU website
-
- https://qemu.org/Contribute/SubmitAPatch
- https://qemu.org/Contribute/TrivialPatches
-
-The QEMU website is also maintained under source control.
-
- git clone https://git.qemu.org/git/qemu-web.git
- https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/
-
-A 'git-publish' utility was created to make above process less
-cumbersome, and is highly recommended for making regular contributions,
-or even just for sending consecutive patch series revisions. It also
-requires a working 'git send-email' setup, and by default doesn't
-automate everything, so you may want to go through the above steps
-manually for once.
-
-For installation instructions, please go to
-
- https://github.com/stefanha/git-publish
-
-The workflow with 'git-publish' is:
-
- $ git checkout master -b my-feature
- $ # work on new commits, add your 'Signed-off-by' lines to each
- $ git publish
-
-Your patch series will be sent and tagged as my-feature-v1 if you need to refer
-back to it in the future.
-
-Sending v2:
-
- $ git checkout my-feature # same topic branch
- $ # making changes to the commits (using 'git rebase', for example)
- $ git publish
-
-Your patch series will be sent with 'v2' tag in the subject and the git tip
-will be tagged as my-feature-v2.
-
-Bug reporting
-=============
-
-The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
-found when running code built from QEMU git or upstream released sources
-should be reported via:
-
- https://bugs.launchpad.net/qemu/
-
-If using QEMU via an operating system vendor pre-built binary package, it
-is preferable to report bugs to the vendor's own bug tracker first. If
-the bug is also known to affect latest upstream code, it can also be
-reported via launchpad.
-
-For additional information on bug reporting consult:
-
- https://qemu.org/Contribute/ReportABug
-
-
-Contact
-=======
-
-The QEMU community can be contacted in a number of ways, with the two
-main methods being email and IRC
-
- - qemu-devel@nongnu.org
- https://lists.nongnu.org/mailman/listinfo/qemu-devel
- - #qemu on irc.oftc.net
-
-Information on additional methods of contacting the community can be
-found online via the QEMU website:
-
- https://qemu.org/Contribute/StartHere
-
--- End
--- /dev/null
+===========
+QEMU README
+===========
+
+QEMU is a generic and open source machine & userspace emulator and
+virtualizer.
+
+QEMU is capable of emulating a complete machine in software without any
+need for hardware virtualization support. By using dynamic translation,
+it achieves very good performance. QEMU can also integrate with the Xen
+and KVM hypervisors to provide emulated hardware while allowing the
+hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
+near native performance for CPUs. When QEMU emulates CPUs directly it is
+capable of running operating systems made for one machine (e.g. an ARMv7
+board) on a different machine (e.g. an x86_64 PC board).
+
+QEMU is also capable of providing userspace API virtualization for Linux
+and BSD kernel interfaces. This allows binaries compiled against one
+architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
+different architecture ABI (e.g. the Linux x86_64 ABI). This does not
+involve any hardware emulation, simply CPU and syscall emulation.
+
+QEMU aims to fit into a variety of use cases. It can be invoked directly
+by users wishing to have full control over its behaviour and settings.
+It also aims to facilitate integration into higher level management
+layers, by providing a stable command line interface and monitor API.
+It is commonly invoked indirectly via the libvirt library when using
+open source applications such as oVirt, OpenStack and virt-manager.
+
+QEMU as a whole is released under the GNU General Public License,
+version 2. For full licensing details, consult the LICENSE file.
+
+
+Building
+========
+
+QEMU is multi-platform software intended to be buildable on all modern
+Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
+of other UNIX targets. The simple steps to build QEMU are:
+
+
+.. code-block:: shell
+
+ mkdir build
+ cd build
+ ../configure
+ make
+
+Additional information can also be found online via the QEMU website:
+
+* `<https://qemu.org/Hosts/Linux>`_
+* `<https://qemu.org/Hosts/Mac>`_
+* `<https://qemu.org/Hosts/W32>`_
+
+
+Submitting patches
+==================
+
+The QEMU source code is maintained under the GIT version control system.
+
+.. code-block:: shell
+
+ git clone https://git.qemu.org/git/qemu.git
+
+When submitting patches, one common approach is to use 'git
+format-patch' and/or 'git send-email' to format & send the mail to the
+qemu-devel@nongnu.org mailing list. All patches submitted must contain
+a 'Signed-off-by' line from the author. Patches should follow the
+guidelines set out in the HACKING.rst and CODING_STYLE.rst files.
+
+Additional information on submitting patches can be found online via
+the QEMU website
+
+* `<https://qemu.org/Contribute/SubmitAPatch>`_
+* `<https://qemu.org/Contribute/TrivialPatches>`_
+
+The QEMU website is also maintained under source control.
+
+.. code-block:: shell
+
+ git clone https://git.qemu.org/git/qemu-web.git
+
+* `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_
+
+A 'git-publish' utility was created to make above process less
+cumbersome, and is highly recommended for making regular contributions,
+or even just for sending consecutive patch series revisions. It also
+requires a working 'git send-email' setup, and by default doesn't
+automate everything, so you may want to go through the above steps
+manually for once.
+
+For installation instructions, please go to
+
+* `<https://github.com/stefanha/git-publish>`_
+
+The workflow with 'git-publish' is:
+
+.. code-block:: shell
+
+ $ git checkout master -b my-feature
+ $ # work on new commits, add your 'Signed-off-by' lines to each
+ $ git publish
+
+Your patch series will be sent and tagged as my-feature-v1 if you need to refer
+back to it in the future.
+
+Sending v2:
+
+.. code-block:: shell
+
+ $ git checkout my-feature # same topic branch
+ $ # making changes to the commits (using 'git rebase', for example)
+ $ git publish
+
+Your patch series will be sent with 'v2' tag in the subject and the git tip
+will be tagged as my-feature-v2.
+
+Bug reporting
+=============
+
+The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
+found when running code built from QEMU git or upstream released sources
+should be reported via:
+
+* `<https://bugs.launchpad.net/qemu/>`_
+
+If using QEMU via an operating system vendor pre-built binary package, it
+is preferable to report bugs to the vendor's own bug tracker first. If
+the bug is also known to affect latest upstream code, it can also be
+reported via launchpad.
+
+For additional information on bug reporting consult:
+
+* `<https://qemu.org/Contribute/ReportABug>`_
+
+
+Contact
+=======
+
+The QEMU community can be contacted in a number of ways, with the two
+main methods being email and IRC
+
+* `<mailto:qemu-devel@nongnu.org>`_
+* `<https://lists.nongnu.org/mailman/listinfo/qemu-devel>`_
+* #qemu on irc.oftc.net
+
+Information on additional methods of contacting the community can be
+found online via the QEMU website:
+
+* `<https://qemu.org/Contribute/StartHere>`_
my @tree_check = (
"COPYING", "MAINTAINERS", "Makefile",
- "README", "docs", "VERSION",
+ "README.rst", "docs", "VERSION",
"vl.c"
);
projects / mirror_qemu.git / commitdiff