# SPDX-License-Identifier: GPL-2.0
menu "UML-specific options"
config UML
bool
default y
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
select ARCH_HAS_CACHE_LINE_SIZE
select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV
select ARCH_HAS_STRNCPY_FROM_USER
select ARCH_HAS_STRNLEN_USER
select ARCH_HAS_STRICT_KERNEL_RWX
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_KASAN if X86_64
select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS
select HAVE_UID16
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_BUGVERBOSE
select HAVE_PAGE_SIZE_4KB
select NO_DMA if !UML_DMA_EMULATION
select OF_EARLY_FLATTREE if OF
select GENERIC_IRQ_SHOW
select GENERIC_CPU_DEVICES
select HAVE_GCC_PLUGINS
select ARCH_SUPPORTS_LTO_CLANG
select ARCH_SUPPORTS_LTO_CLANG_THIN
select TRACE_IRQFLAGS_SUPPORT
select TTY # Needed for line.c
select HAVE_ARCH_VMAP_STACK
select HAVE_RUST
select ARCH_HAS_UBSAN
select HAVE_ARCH_TRACEHOOK
select HAVE_SYSCALL_TRACEPOINTS
select THREAD_INFO_IN_TASK
config MMU
bool
default y
config UML_DMA_EMULATION
bool
config NO_IOMEM
bool "disable IOMEM" if EXPERT
depends on !INDIRECT_IOMEM
default y
config UML_IOMEM_EMULATION
bool
select INDIRECT_IOMEM
select GENERIC_PCI_IOMAP
config ISA
bool
config SBUS
bool
config LOCKDEP_SUPPORT
bool
default y
config STACKTRACE_SUPPORT
bool
default y
select STACKTRACE
config GENERIC_CALIBRATE_DELAY
bool
default y
config HZ
int
default 100
config NR_CPUS
int
range 1 1
default 1
source "arch/$(HEADER_ARCH)/um/Kconfig"
config MAY_HAVE_RUNTIME_DEPS
bool
config STATIC_LINK
bool "Force a static link"
depends on !MAY_HAVE_RUNTIME_DEPS
help
This option gives you the ability to force a static link of UML.
Normally, UML is linked as a shared binary. This is inconvenient for
use in a chroot jail. So, if you intend to run UML inside a chroot,
you probably want to say Y here.
Additionally, this option enables using higher memory spaces (up to
2.75G) for UML.
NOTE: This option is incompatible with some networking features which
depend on features that require being dynamically loaded (like NSS).
config LD_SCRIPT_STATIC
bool
default y
depends on STATIC_LINK
config LD_SCRIPT_DYN
bool
default y
depends on !LD_SCRIPT_STATIC
config LD_SCRIPT_DYN_RPATH
bool "set rpath in the binary" if EXPERT
default y
depends on LD_SCRIPT_DYN
help
Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
explicitly.
You may need to turn this off if compiling for nix systems
that have their libraries in random /nix directories and
might otherwise unexpected use libraries from /lib or /lib64
instead of the desired ones.
config HOSTFS
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 UML user
access files stored on the host. It does not require any
network connection between the Host and UML. An example use of
this might be:
mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
where /tmp/fromhost is an empty directory inside UML and
/tmp/umlshare is a directory on the host with files the UML 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 M here; otherwise say N.
config MCONSOLE
bool "Management console"
depends on PROC_FS
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 MAGIC_SYSRQ
bool "Magic SysRq key"
depends on MCONSOLE
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). A 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 UML, 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 KERNEL_STACK_ORDER
int "Kernel stack size order"
default 2 if 64BIT
range 2 10 if 64BIT
default 1 if !64BIT
help
This option determines the size of UML kernel stacks. They will
be 1 << order pages. The default is OK unless you're running Valgrind
on UML, in which case, set this to 3.
It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT 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 MMAPPER
tristate "iomem emulation driver"
help
This driver allows a host file to be used as emulated IO memory inside
UML.
config PGTABLE_LEVELS
int
default 4 if 64BIT
default 2 if !64BIT
config UML_TIME_TRAVEL_SUPPORT
bool
prompt "Support time-travel mode (e.g. for test execution)"
# inf-cpu mode is incompatible with the benchmarking
depends on !RAID6_PQ_BENCHMARK
depends on !SMP
help
Enable this option to support time travel inside the UML 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.
config UML_MAX_USERSPACE_ITERATIONS
int
prompt "Maximum number of unscheduled userspace iterations"
default 10000
depends on UML_TIME_TRAVEL_SUPPORT
help
In UML inf-cpu and ext time-travel mode userspace can run without being
interrupted. This will eventually overwhelm the kernel and create OOM
situations (mainly RCU not running). This setting specifies the number
of kernel/userspace switches (minor/major page fault, signal or syscall)
for the same userspace thread before the sched_clock is advanced by a
jiffie to trigger scheduling.
Setting it to zero disables the feature.
config KASAN_SHADOW_OFFSET
hex
depends on KASAN
default 0x100000000000
help
This is the offset at which the ~16TB of shadow memory is
mapped and used by KASAN for memory debugging. This can be any
address that has at least KASAN_SHADOW_SIZE (total address space divided
by 8) amount of space so that the KASAN shadow memory does not conflict
with anything. The default is 0x100000000000, which works even if mem is
set to a large value. On low-memory systems, try 0x7fff8000, as it fits
into the immediate of most instructions, improving performance.
endmenu
source "arch/um/drivers/Kconfig"
config ARCH_SUSPEND_POSSIBLE
def_bool y
menu "Power management options"
source "kernel/power/Kconfig"
endmenu
