arch/um/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0
   2
   3 menu "UML-specific options"
   4
   5 config UML
   6         bool
   7         default y
   8         select ARCH_HAS_KCOV
   9         select ARCH_NO_PREEMPT
  10         select HAVE_ARCH_AUDITSYSCALL
  11         select HAVE_ARCH_SECCOMP_FILTER
  12         select HAVE_ASM_MODVERSIONS
  13         select HAVE_UID16
  14         select HAVE_FUTEX_CMPXCHG if FUTEX
  15         select HAVE_DEBUG_KMEMLEAK
  16         select HAVE_DEBUG_BUGVERBOSE
  17         select NO_DMA
  18         select ARCH_HAS_SET_MEMORY
  19         select GENERIC_IRQ_SHOW
  20         select GENERIC_CPU_DEVICES
  21         select HAVE_GCC_PLUGINS
  22         select SET_FS
  23         select TTY # Needed for line.c
  24
  25 config MMU
  26         bool
  27         default y
  28
  29 config NO_IOMEM
  30         def_bool y
  31
  32 config ISA
  33         bool
  34
  35 config SBUS
  36         bool
  37
  38 config TRACE_IRQFLAGS_SUPPORT
  39         bool
  40         default y
  41
  42 config LOCKDEP_SUPPORT
  43         bool
  44         default y
  45
  46 config STACKTRACE_SUPPORT
  47         bool
  48         default y
  49         select STACKTRACE
  50
  51 config GENERIC_CALIBRATE_DELAY
  52         bool
  53         default y
  54
  55 config HZ
  56         int
  57         default 100
  58
  59 config NR_CPUS
  60         int
  61         range 1 1
  62         default 1
  63
  64 source "arch/$(HEADER_ARCH)/um/Kconfig"
  65
  66 config MAY_HAVE_RUNTIME_DEPS
  67         bool
  68
  69 config STATIC_LINK
  70         bool "Force a static link"
  71         depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
  72         help
  73           This option gives you the ability to force a static link of UML.
  74           Normally, UML is linked as a shared binary.  This is inconvenient for
  75           use in a chroot jail.  So, if you intend to run UML inside a chroot,
  76           you probably want to say Y here.
  77           Additionally, this option enables using higher memory spaces (up to
  78           2.75G) for UML.
  79
  80           NOTE: This option is incompatible with some networking features which
  81           depend on features that require being dynamically loaded (like NSS).
  82
  83 config LD_SCRIPT_STATIC
  84         bool
  85         default y
  86         depends on STATIC_LINK
  87
  88 config LD_SCRIPT_DYN
  89         bool
  90         default y
  91         depends on !LD_SCRIPT_STATIC
  92         select MODULE_REL_CRCS if MODVERSIONS
  93
  94 config HOSTFS
  95         tristate "Host filesystem"
  96         help
  97           While the User-Mode Linux port uses its own root file system for
  98           booting and normal file access, this module lets the UML user
  99           access files stored on the host.  It does not require any
 100           network connection between the Host and UML.  An example use of
 101           this might be:
 102
 103           mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
 104
 105           where /tmp/fromhost is an empty directory inside UML and
 106           /tmp/umlshare is a directory on the host with files the UML user
 107           wishes to access.
 108
 109           For more information, see
 110           <http://user-mode-linux.sourceforge.net/hostfs.html>.
 111
 112           If you'd like to be able to work with files stored on the host,
 113           say Y or M here; otherwise say N.
 114
 115 config MCONSOLE
 116         bool "Management console"
 117         depends on PROC_FS
 118         default y
 119         help
 120           The user mode linux management console is a low-level interface to
 121           the kernel, somewhat like the i386 SysRq interface.  Since there is
 122           a full-blown operating system running under every user mode linux
 123           instance, there is much greater flexibility possible than with the
 124           SysRq mechanism.
 125
 126           If you answer 'Y' to this option, to use this feature, you need the
 127           mconsole client (called uml_mconsole) which is present in CVS in
 128           2.4.5-9um and later (path /tools/mconsole), and is also in the
 129           distribution RPM package in 2.4.6 and later.
 130
 131           It is safe to say 'Y' here.
 132
 133 config MAGIC_SYSRQ
 134         bool "Magic SysRq key"
 135         depends on MCONSOLE
 136         help
 137           If you say Y here, you will have some control over the system even
 138           if the system crashes for example during kernel debugging (e.g., you
 139           will be able to flush the buffer cache to disk, reboot the system
 140           immediately or dump some status information). A key for each of the
 141           possible requests is provided.
 142
 143           This is the feature normally accomplished by pressing a key
 144           while holding SysRq (Alt+PrintScreen).
 145
 146           On UML, this is accomplished by sending a "sysrq" command with
 147           mconsole, followed by the letter for the requested command.
 148
 149           The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
 150           unless you really know what this hack does.
 151
 152 config KERNEL_STACK_ORDER
 153         int "Kernel stack size order"
 154         default 2 if 64BIT
 155         range 2 10 if 64BIT
 156         default 1 if !64BIT
 157         help
 158           This option determines the size of UML kernel stacks.  They will
 159           be 1 << order pages.  The default is OK unless you're running Valgrind
 160           on UML, in which case, set this to 3.
 161           It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
 162           older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
 163           increase in the size of the state which needs to be saved when handling
 164           signals.
 165
 166 config MMAPPER
 167         tristate "iomem emulation driver"
 168         help
 169           This driver allows a host file to be used as emulated IO memory inside
 170           UML.
 171
 172 config PGTABLE_LEVELS
 173         int
 174         default 3 if 3_LEVEL_PGTABLES
 175         default 2
 176
 177 config UML_TIME_TRAVEL_SUPPORT
 178         bool
 179         prompt "Support time-travel mode (e.g. for test execution)"
 180         # inf-cpu mode is incompatible with the benchmarking
 181         depends on !RAID6_PQ_BENCHMARK
 182         depends on !SMP
 183         help
 184           Enable this option to support time travel inside the UML instance.
 185
 186           After enabling this option, two modes are accessible at runtime
 187           (selected by the kernel command line), see the kernel's command-
 188           line help for more details.
 189
 190           It is safe to say Y, but you probably don't need this.
 191
 192 endmenu
 193
 194 source "arch/um/drivers/Kconfig"
 195
 196 config ARCH_SUSPEND_POSSIBLE
 197         def_bool y
 198
 199 source "kernel/power/Kconfig"