# SPDX-License-Identifier: GPL-2.0
menu "UML-specific options"
config [31mCONFIG_UML[0m
bool
default y
select [31mCONFIG_ARCH_HAS_KCOV[0m
select [31mCONFIG_ARCH_NO_PREEMPT[0m
select [31mCONFIG_HAVE_ARCH_AUDITSYSCALL[0m
select [31mCONFIG_HAVE_ARCH_SECCOMP_FILTER[0m
select [31mCONFIG_HAVE_ASM_MODVERSIONS[0m
select [31mCONFIG_HAVE_UID16[0m
select [31mCONFIG_HAVE_FUTEX_CMPXCHG[0m if [31mCONFIG_FUTEX[0m
select [31mCONFIG_HAVE_DEBUG_KMEMLEAK[0m
select [31mCONFIG_HAVE_DEBUG_BUGVERBOSE[0m
select [31mCONFIG_GENERIC_IRQ_SHOW[0m
select [31mCONFIG_GENERIC_CPU_DEVICES[0m
select [31mCONFIG_GENERIC_CLOCKEVENTS[0m
select [31mCONFIG_HAVE_GCC_PLUGINS[0m
select [31mCONFIG_TTY[0m # Needed for line.c
config [31mCONFIG_MMU[0m
bool
default y
config [31mCONFIG_NO_IOMEM[0m
def_bool y
config [31mCONFIG_ISA[0m
bool
config [31mCONFIG_SBUS[0m
bool
config [31mCONFIG_TRACE_IRQFLAGS_SUPPORT[0m
bool
default y
config [31mCONFIG_LOCKDEP_SUPPORT[0m
bool
default y
config [31mCONFIG_STACKTRACE_SUPPORT[0m
bool
default y
select [31mCONFIG_STACKTRACE[0m
config [31mCONFIG_GENERIC_CALIBRATE_DELAY[0m
bool
default y
config [31mCONFIG_HZ[0m
int
default 100
config [31mCONFIG_NR_CPUS[0m
int
range 1 1
default 1
source "arch/$(HEADER_ARCH)/um/Kconfig"
config [31mCONFIG_STATIC_LINK[0m
bool "Force a static link"
default n
help
This option gives you the ability to force a static link of [31mCONFIG_UML[0m.
Normally, [31mCONFIG_UML[0m is linked as a shared binary. This is inconvenient for
use in a chroot jail. So, if you intend to run [31mCONFIG_UML[0m inside a chroot,
you probably want to say Y here.
Additionally, this option enables using higher memory spaces (up to
2.75G) for [31mCONFIG_UML[0m.
config [31mCONFIG_LD_SCRIPT_STATIC[0m
bool
default y
depends on [31mCONFIG_STATIC_LINK[0m
config [31mCONFIG_LD_SCRIPT_DYN[0m
bool
default y
depends on ![31mCONFIG_LD_SCRIPT_STATIC[0m
select [31mCONFIG_MODULE_REL_CRCS[0m if [31mCONFIG_MODVERSIONS[0m
config [31mCONFIG_HOSTFS[0m
tristate "Host filesystem"
help
While the User-Mode Linux port uses its own root file system for
booting and normal file access, this module lets the [31mCONFIG_UML[0m user
access files stored on the host. It does not require any
network connection between the Host and [31mCONFIG_UML[0m. An example use of
this might be:
mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
where /tmp/fromhost is an empty directory inside [31mCONFIG_UML[0m and
/tmp/umlshare is a directory on the host with files the [31mCONFIG_UML[0m user
wishes to access.
For more information, see
<http://user-mode-linux.sourceforge.net/hostfs.html>.
If you'd like to be able to work with files stored on the host,
say Y or [31mCONFIG_M[0m here; otherwise say N.
config [31mCONFIG_MCONSOLE[0m
bool "Management console"
depends on [31mCONFIG_PROC_FS[0m
default y
help
The user mode linux management console is a low-level interface to
the kernel, somewhat like the i386 SysRq interface. Since there is
a full-blown operating system running under every user mode linux
instance, there is much greater flexibility possible than with the
SysRq mechanism.
If you answer 'Y' to this option, to use this feature, you need the
mconsole client (called uml_mconsole) which is present in CVS in
2.4.5-9um and later (path /tools/mconsole), and is also in the
distribution RPM package in 2.4.6 and later.
It is safe to say 'Y' here.
config [31mCONFIG_MAGIC_SYSRQ[0m
bool "Magic SysRq key"
depends on [31mCONFIG_MCONSOLE[0m
help
If you say Y here, you will have some control over the system even
if the system crashes for example during kernel debugging (e.g., you
will be able to flush the buffer cache to disk, reboot the system
immediately or dump some status information). [31mCONFIG_A[0m key for each of the
possible requests is provided.
This is the feature normally accomplished by pressing a key
while holding SysRq (Alt+PrintScreen).
On [31mCONFIG_UML[0m, this is accomplished by sending a "sysrq" command with
mconsole, followed by the letter for the requested command.
The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
unless you really know what this hack does.
config [31mCONFIG_KERNEL_STACK_ORDER[0m
int "Kernel stack size order"
default 2 if [31mCONFIG_64BIT[0m
range 2 10 if [31mCONFIG_64BIT[0m
default 1 if ![31mCONFIG_64BIT[0m
help
This option determines the size of [31mCONFIG_UML[0m kernel stacks. They will
be 1 << order pages. The default is OK unless you're running Valgrind
on [31mCONFIG_UML[0m, in which case, set this to 3.
It is possible to reduce the stack to 1 for [31mCONFIG_64BIT[0m and 0 for [31mCONFIG_32BIT[0m on
older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
increase in the size of the state which needs to be saved when handling
signals.
config [31mCONFIG_MMAPPER[0m
tristate "iomem emulation driver"
help
This driver allows a host file to be used as emulated IO memory inside
[31mCONFIG_UML[0m.
config [31mCONFIG_NO_DMA[0m
def_bool y
config [31mCONFIG_PGTABLE_LEVELS[0m
int
default 3 if [31mCONFIG_3_LEVEL_PGTABLES[0m
default 2
config [31mCONFIG_SECCOMP[0m
def_bool y
prompt "Enable seccomp to safely compute untrusted bytecode"
---help---
This kernel feature is useful for number crunching applications
that may need to compute untrusted bytecode during their
execution. By using pipes or other transports made available to
the process as file descriptors supporting the read/write
syscalls, it's possible to isolate those applications in
their own address space using seccomp. Once seccomp is
enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
and the task is only allowed to execute a few safe syscalls
defined by each seccomp mode.
If unsure, say Y.
config [31mCONFIG_UML_TIME_TRAVEL_SUPPORT[0m
bool
prompt "Support time-travel mode (e.g. for test execution)"
help
Enable this option to support time travel inside the [31mCONFIG_UML[0m instance.
After enabling this option, two modes are accessible at runtime
(selected by the kernel command line), see the kernel's command-
line help for more details.
It is safe to say Y, but you probably don't need this.
endmenu
source "arch/um/drivers/Kconfig"