LXR linux/arch/um/Kconfig.um

   1# SPDX-License-Identifier: GPL-2.0
   2config STATIC_LINK
   3        bool "Force a static link"
   4        default n
   5        help
   6          This option gives you the ability to force a static link of UML.
   7          Normally, UML is linked as a shared binary.  This is inconvenient for
   8          use in a chroot jail.  So, if you intend to run UML inside a chroot,
   9          you probably want to say Y here.
  10          Additionally, this option enables using higher memory spaces (up to
  11          2.75G) for UML.
  12
  13source "mm/Kconfig"
  14
  15config LD_SCRIPT_STATIC
  16        bool
  17        default y
  18        depends on STATIC_LINK
  19
  20config LD_SCRIPT_DYN
  21        bool
  22        default y
  23        depends on !LD_SCRIPT_STATIC
  24        select MODULE_REL_CRCS if MODVERSIONS
  25
  26source "fs/Kconfig.binfmt"
  27
  28config HOSTFS
  29        tristate "Host filesystem"
  30        help
  31          While the User-Mode Linux port uses its own root file system for
  32          booting and normal file access, this module lets the UML user
  33          access files stored on the host.  It does not require any
  34          network connection between the Host and UML.  An example use of
  35          this might be:
  36
  37          mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
  38
  39          where /tmp/fromhost is an empty directory inside UML and
  40          /tmp/umlshare is a directory on the host with files the UML user
  41          wishes to access.
  42
  43          For more information, see
  44          <http://user-mode-linux.sourceforge.net/hostfs.html>.
  45
  46          If you'd like to be able to work with files stored on the host,
  47          say Y or M here; otherwise say N.
  48
  49config MCONSOLE
  50        bool "Management console"
  51        depends on PROC_FS
  52        default y
  53        help
  54          The user mode linux management console is a low-level interface to
  55          the kernel, somewhat like the i386 SysRq interface.  Since there is
  56          a full-blown operating system running under every user mode linux
  57          instance, there is much greater flexibility possible than with the
  58          SysRq mechanism.
  59
  60          If you answer 'Y' to this option, to use this feature, you need the
  61          mconsole client (called uml_mconsole) which is present in CVS in
  62          2.4.5-9um and later (path /tools/mconsole), and is also in the
  63          distribution RPM package in 2.4.6 and later.
  64
  65          It is safe to say 'Y' here.
  66
  67config MAGIC_SYSRQ
  68        bool "Magic SysRq key"
  69        depends on MCONSOLE
  70        help
  71          If you say Y here, you will have some control over the system even
  72          if the system crashes for example during kernel debugging (e.g., you
  73          will be able to flush the buffer cache to disk, reboot the system
  74          immediately or dump some status information). A key for each of the
  75          possible requests is provided.
  76
  77          This is the feature normally accomplished by pressing a key
  78          while holding SysRq (Alt+PrintScreen).
  79
  80          On UML, this is accomplished by sending a "sysrq" command with
  81          mconsole, followed by the letter for the requested command.
  82
  83          The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
  84          unless you really know what this hack does.
  85
  86config KERNEL_STACK_ORDER
  87        int "Kernel stack size order"
  88        default 1 if 64BIT
  89        range 1 10 if 64BIT
  90        default 0 if !64BIT
  91        help
  92          This option determines the size of UML kernel stacks.  They will
  93          be 1 << order pages.  The default is OK unless you're running Valgrind
  94          on UML, in which case, set this to 3.
  95
  96config MMAPPER
  97        tristate "iomem emulation driver"
  98        help
  99          This driver allows a host file to be used as emulated IO memory inside
 100          UML.
 101
 102config NO_DMA
 103        def_bool y
 104
 105config PGTABLE_LEVELS
 106        int
 107        default 3 if 3_LEVEL_PGTABLES
 108        default 2
 109
 110config SECCOMP
 111        def_bool y
 112        prompt "Enable seccomp to safely compute untrusted bytecode"
 113        ---help---
 114          This kernel feature is useful for number crunching applications
 115          that may need to compute untrusted bytecode during their
 116          execution. By using pipes or other transports made available to
 117          the process as file descriptors supporting the read/write
 118          syscalls, it's possible to isolate those applications in
 119          their own address space using seccomp. Once seccomp is
 120          enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
 121          and the task is only allowed to execute a few safe syscalls
 122          defined by each seccomp mode.
 123
 124          If unsure, say Y.
 125