intel_iommu: Fix root_scalable migration breakage

[mirror_qemu.git] / qemu-tech.texi

diff --git a/qemu-tech.texi b/qemu-tech.texi
index b418a41b7874d97ec31c5c0ec5b065816e4ef0c8..7c3d1f05e132f79760b49b682b8eebb533e81010 100644 (file)
--- a/qemu-tech.texi
+++ b/qemu-tech.texi
@@ -1,45 +1,16 @@
-\input texinfo @c -*- texinfo -*-
-@c %**start of header
-@setfilename qemu-tech.info
-
-@documentlanguage en
-@documentencoding UTF-8
-
-@settitle QEMU Internals
-@exampleindent 0
-@paragraphindent 0
-@c %**end of header
-
-@ifinfo
-@direntry
-* QEMU Internals: (qemu-tech).   The QEMU Emulator Internals.
-@end direntry
-@end ifinfo
-
-@iftex
-@titlepage
-@sp 7
-@center @titlefont{QEMU Internals}
-@sp 3
-@end titlepage
-@end iftex
-
-@ifnottex
-@node Top
-@top
+@node Implementation notes
+@appendix Implementation notes
 
 @menu
 * CPU emulation::
 * Translator Internals::
 * QEMU compared to other emulators::
+* Managed start up options::
 * Bibliography::
 @end menu
-@end ifnottex
-
-@contents
 
 @node CPU emulation
-@chapter CPU emulation
+@section CPU emulation
 
 @menu
 * x86::     x86 and x86-64 emulation
@@ -51,7 +22,7 @@
 @end menu
 
 @node x86
-@section x86 and x86-64 emulation
+@subsection x86 and x86-64 emulation
 
 QEMU x86 target features:
 
@@ -86,7 +57,7 @@ normal use.
 @end itemize
 
 @node ARM
-@section ARM emulation
+@subsection ARM emulation
 
 @itemize
 
@@ -99,7 +70,7 @@ normal use.
 @end itemize
 
 @node MIPS
-@section MIPS emulation
+@subsection MIPS emulation
 
 @itemize
 
@@ -126,7 +97,7 @@ Current QEMU limitations:
 @end itemize
 
 @node PPC
-@section PowerPC emulation
+@subsection PowerPC emulation
 
 @itemize
 
@@ -138,7 +109,7 @@ FPU and MMU.
 @end itemize
 
 @node SPARC
-@section Sparc32 and Sparc64 emulation
+@subsection Sparc32 and Sparc64 emulation
 
 @itemize
 
@@ -166,7 +137,7 @@ Current QEMU limitations:
 @end itemize
 
 @node Xtensa
-@section Xtensa emulation
+@subsection Xtensa emulation
 
 @itemize
 
@@ -191,7 +162,7 @@ may be created from overlay with minimal amount of hand-written code.
 @end itemize
 
 @node Translator Internals
-@chapter Translator Internals
+@section Translator Internals
 
 QEMU is a dynamic translator. When it first encounters a piece of code,
 it converts it to the host instruction set. Usually dynamic translators
@@ -294,7 +265,7 @@ translation blocks.
 @end table
 
 @node QEMU compared to other emulators
-@chapter QEMU compared to other emulators
+@section QEMU compared to other emulators
 
 Like bochs [1], QEMU emulates an x86 CPU. But QEMU is much faster than
 bochs as it uses dynamic compilation. Bochs is closely tied to x86 PC
@@ -344,8 +315,44 @@ VirtualBox [9], Xen [10] and KVM [11] are based on QEMU. QEMU-SystemC
 [12] uses QEMU to simulate a system where some hardware devices are
 developed in SystemC.
 
+@node Managed start up options
+@section Managed start up options
+
+In system mode emulation, it's possible to create a VM in a paused state using
+the -S command line option. In this state the machine is completely initialized
+according to command line options and ready to execute VM code but VCPU threads
+are not executing any code. The VM state in this paused state depends on the way
+QEMU was started. It could be in:
+@table @asis
+@item initial state (after reset/power on state)
+@item with direct kernel loading, the initial state could be amended to execute
+code loaded by QEMU in the VM's RAM and with incoming migration
+@item with incoming migration, initial state will by amended with the migrated
+machine state after migration completes.
+@end table
+
+This paused state is typically used by users to query machine state and/or
+additionally configure the machine (by hotplugging devices) in runtime before
+allowing VM code to run.
+
+However, at the -S pause point, it's impossible to configure options that affect
+initial VM creation (like: -smp/-m/-numa ...) or cold plug devices. The
+experimental --preconfig command line option  allows pausing QEMU
+before the initial VM creation, in a ``preconfig'' state, where additional
+queries and configuration can be performed via QMP before moving on to
+the resulting configuration startup. In the preconfig state, QEMU only allows
+a limited set of commands over the QMP monitor, where the commands do not
+depend on an initialized machine, including but not limited to:
+@table @asis
+@item qmp_capabilities
+@item query-qmp-schema
+@item query-commands
+@item query-status
+@item x-exit-preconfig
+@end table
+
 @node Bibliography
-@chapter Bibliography
+@section Bibliography
 
 @table @asis
 
@@ -399,5 +406,3 @@ Kernel Based Virtual Machine (KVM).
 QEMU-SystemC, a hardware co-simulator.
 
 @end table
-
-@bye