arch/um/Kconfig.um

   1 config STATIC_LINK
   2         bool "Force a static link"
   3         default n
   4         help
   5           This option gives you the ability to force a static link of UML.
   6           Normally, UML is linked as a shared binary.  This is inconvenient for
   7           use in a chroot jail.  So, if you intend to run UML inside a chroot,
   8           you probably want to say Y here.
   9           Additionally, this option enables using higher memory spaces (up to
  10           2.75G) for UML.
  11
  12 source "mm/Kconfig"
  13
  14 config LD_SCRIPT_STATIC
  15         bool
  16         default y
  17         depends on STATIC_LINK
  18
  19 config LD_SCRIPT_DYN
  20         bool
  21         default y
  22         depends on !LD_SCRIPT_STATIC
  23
  24 source "fs/Kconfig.binfmt"
  25
  26 config HOSTFS
  27         tristate "Host filesystem"
  28         help
  29           While the User-Mode Linux port uses its own root file system for
  30           booting and normal file access, this module lets the UML user
  31           access files stored on the host.  It does not require any
  32           network connection between the Host and UML.  An example use of
  33           this might be:
  34
  35           mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
  36
  37           where /tmp/fromhost is an empty directory inside UML and
  38           /tmp/umlshare is a directory on the host with files the UML user
  39           wishes to access.
  40
  41           For more information, see
  42           <http://user-mode-linux.sourceforge.net/hostfs.html>.
  43
  44           If you'd like to be able to work with files stored on the host,
  45           say Y or M here; otherwise say N.
  46
  47 config MCONSOLE
  48         bool "Management console"
  49         depends on PROC_FS
  50         default y
  51         help
  52           The user mode linux management console is a low-level interface to
  53           the kernel, somewhat like the i386 SysRq interface.  Since there is
  54           a full-blown operating system running under every user mode linux
  55           instance, there is much greater flexibility possible than with the
  56           SysRq mechanism.
  57
  58           If you answer 'Y' to this option, to use this feature, you need the
  59           mconsole client (called uml_mconsole) which is present in CVS in
  60           2.4.5-9um and later (path /tools/mconsole), and is also in the
  61           distribution RPM package in 2.4.6 and later.
  62
  63           It is safe to say 'Y' here.
  64
  65 config MAGIC_SYSRQ
  66         bool "Magic SysRq key"
  67         depends on MCONSOLE
  68         help
  69           If you say Y here, you will have some control over the system even
  70           if the system crashes for example during kernel debugging (e.g., you
  71           will be able to flush the buffer cache to disk, reboot the system
  72           immediately or dump some status information). A key for each of the
  73           possible requests is provided.
  74
  75           This is the feature normally accomplished by pressing a key
  76           while holding SysRq (Alt+PrintScreen).
  77
  78           On UML, this is accomplished by sending a "sysrq" command with
  79           mconsole, followed by the letter for the requested command.
  80
  81           The keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  82           unless you really know what this hack does.
  83
  84 config KERNEL_STACK_ORDER
  85         int "Kernel stack size order"
  86         default 1 if 64BIT
  87         range 1 10 if 64BIT
  88         default 0 if !64BIT
  89         help
  90           This option determines the size of UML kernel stacks.  They will
  91           be 1 << order pages.  The default is OK unless you're running Valgrind
  92           on UML, in which case, set this to 3.
  93
  94 config MMAPPER
  95         tristate "iomem emulation driver"
  96         help
  97           This driver allows a host file to be used as emulated IO memory inside
  98           UML.
  99
 100 config NO_DMA
 101         def_bool y
 102
 103 config PGTABLE_LEVELS
 104         int
 105         default 3 if 3_LEVEL_PGTABLES
 106         default 2
 107
 108 config SECCOMP
 109         def_bool y
 110         prompt "Enable seccomp to safely compute untrusted bytecode"
 111         ---help---
 112           This kernel feature is useful for number crunching applications
 113           that may need to compute untrusted bytecode during their
 114           execution. By using pipes or other transports made available to
 115           the process as file descriptors supporting the read/write
 116           syscalls, it's possible to isolate those applications in
 117           their own address space using seccomp. Once seccomp is
 118           enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
 119           and the task is only allowed to execute a few safe syscalls
 120           defined by each seccomp mode.
 121
 122           If unsure, say Y.