# SPDX-License-Identifier: GPL-2.0 menu "UML-specific options" config UML bool default y select ARCH_WANTS_DYNAMIC_TASK_STRUCT 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 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 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 HAS_IOPORT select GENERIC_PCI_IOMAP select GENERIC_IOMAP select NO_GENERIC_PCI_IOPORT_MAP config NO_IOPORT_MAP def_bool !UML_IOMEM_EMULATION 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 config ARCH_HAS_CACHE_LINE_SIZE def_bool y 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 . 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 . 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