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![Patricia Alfonso](/assets/img/avatar_default.png)
Make KASAN run on User Mode Linux on x86_64. The UML-specific KASAN initializer uses mmap to map the ~16TB of shadow memory to the location defined by KASAN_SHADOW_OFFSET. kasan_init() utilizes constructors to initialize KASAN before main(). The location of the KASAN shadow memory, starting at KASAN_SHADOW_OFFSET, can be configured using the KASAN_SHADOW_OFFSET option. The default location of this offset is 0x100000000000, which keeps it out-of-the-way even on UML setups with more "physical" memory. For low-memory setups, 0x7fff8000 can be used instead, which fits in an immediate and is therefore faster, as suggested by Dmitry Vyukov. There is usually enough free space at this location; however, it is a config option so that it can be easily changed if needed. Note that, unlike KASAN on other architectures, vmalloc allocations still use the shadow memory allocated upfront, rather than allocating and free-ing it per-vmalloc allocation. If another architecture chooses to go down the same path, we should replace the checks for CONFIG_UML with something more generic, such as: - A CONFIG_KASAN_NO_SHADOW_ALLOC option, which architectures could set - or, a way of having architecture-specific versions of these vmalloc and module shadow memory allocation options. Also note that, while UML supports both KASAN in inline mode (CONFIG_KASAN_INLINE) and static linking (CONFIG_STATIC_LINK), it does not support both at the same time. Signed-off-by: Patricia Alfonso <trishalfonso@google.com> Co-developed-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: David Gow <davidgow@google.com> Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Signed-off-by: Richard Weinberger <richard@nod.at>
244 lines
6.6 KiB
Text
244 lines
6.6 KiB
Text
# SPDX-License-Identifier: GPL-2.0
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menu "UML-specific options"
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config UML
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bool
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default y
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select ARCH_EPHEMERAL_INODES
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select ARCH_HAS_GCOV_PROFILE_ALL
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select ARCH_HAS_KCOV
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select ARCH_HAS_STRNCPY_FROM_USER
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select ARCH_HAS_STRNLEN_USER
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select ARCH_NO_PREEMPT
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select HAVE_ARCH_AUDITSYSCALL
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select HAVE_ARCH_KASAN if X86_64
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select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
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select HAVE_ARCH_SECCOMP_FILTER
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select HAVE_ASM_MODVERSIONS
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select HAVE_UID16
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select HAVE_DEBUG_KMEMLEAK
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select HAVE_DEBUG_BUGVERBOSE
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select NO_DMA if !UML_DMA_EMULATION
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select OF_EARLY_FLATTREE if OF
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select GENERIC_IRQ_SHOW
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select GENERIC_CPU_DEVICES
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select HAVE_GCC_PLUGINS
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select TRACE_IRQFLAGS_SUPPORT
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select TTY # Needed for line.c
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select HAVE_ARCH_VMAP_STACK
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config MMU
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bool
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default y
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config UML_DMA_EMULATION
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bool
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config NO_IOMEM
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bool "disable IOMEM" if EXPERT
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depends on !INDIRECT_IOMEM
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default y
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config UML_IOMEM_EMULATION
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bool
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select INDIRECT_IOMEM
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select GENERIC_PCI_IOMAP
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select GENERIC_IOMAP
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select NO_GENERIC_PCI_IOPORT_MAP
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config NO_IOPORT_MAP
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def_bool y
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config ISA
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bool
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config SBUS
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bool
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config LOCKDEP_SUPPORT
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bool
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default y
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config STACKTRACE_SUPPORT
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bool
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default y
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select STACKTRACE
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config GENERIC_CALIBRATE_DELAY
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bool
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default y
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config HZ
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int
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default 100
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config NR_CPUS
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int
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range 1 1
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default 1
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config ARCH_HAS_CACHE_LINE_SIZE
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def_bool y
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source "arch/$(HEADER_ARCH)/um/Kconfig"
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config MAY_HAVE_RUNTIME_DEPS
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bool
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config STATIC_LINK
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bool "Force a static link"
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depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
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help
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This option gives you the ability to force a static link of UML.
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Normally, UML is linked as a shared binary. This is inconvenient for
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use in a chroot jail. So, if you intend to run UML inside a chroot,
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you probably want to say Y here.
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Additionally, this option enables using higher memory spaces (up to
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2.75G) for UML.
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NOTE: This option is incompatible with some networking features which
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depend on features that require being dynamically loaded (like NSS).
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config LD_SCRIPT_STATIC
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bool
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default y
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depends on STATIC_LINK
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config LD_SCRIPT_DYN
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bool
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default y
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depends on !LD_SCRIPT_STATIC
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config LD_SCRIPT_DYN_RPATH
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bool "set rpath in the binary" if EXPERT
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default y
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depends on LD_SCRIPT_DYN
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help
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Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
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explicitly.
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You may need to turn this off if compiling for nix systems
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that have their libraries in random /nix directories and
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might otherwise unexpected use libraries from /lib or /lib64
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instead of the desired ones.
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config HOSTFS
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tristate "Host filesystem"
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help
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While the User-Mode Linux port uses its own root file system for
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booting and normal file access, this module lets the UML user
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access files stored on the host. It does not require any
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network connection between the Host and UML. An example use of
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this might be:
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mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
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where /tmp/fromhost is an empty directory inside UML and
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/tmp/umlshare is a directory on the host with files the UML user
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wishes to access.
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For more information, see
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<http://user-mode-linux.sourceforge.net/hostfs.html>.
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If you'd like to be able to work with files stored on the host,
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say Y or M here; otherwise say N.
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config MCONSOLE
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bool "Management console"
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depends on PROC_FS
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default y
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help
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The user mode linux management console is a low-level interface to
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the kernel, somewhat like the i386 SysRq interface. Since there is
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a full-blown operating system running under every user mode linux
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instance, there is much greater flexibility possible than with the
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SysRq mechanism.
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If you answer 'Y' to this option, to use this feature, you need the
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mconsole client (called uml_mconsole) which is present in CVS in
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2.4.5-9um and later (path /tools/mconsole), and is also in the
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distribution RPM package in 2.4.6 and later.
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It is safe to say 'Y' here.
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config MAGIC_SYSRQ
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bool "Magic SysRq key"
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depends on MCONSOLE
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help
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If you say Y here, you will have some control over the system even
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if the system crashes for example during kernel debugging (e.g., you
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will be able to flush the buffer cache to disk, reboot the system
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immediately or dump some status information). A key for each of the
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possible requests is provided.
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This is the feature normally accomplished by pressing a key
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while holding SysRq (Alt+PrintScreen).
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On UML, this is accomplished by sending a "sysrq" command with
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mconsole, followed by the letter for the requested command.
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The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
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unless you really know what this hack does.
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config KERNEL_STACK_ORDER
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int "Kernel stack size order"
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default 2 if 64BIT
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range 2 10 if 64BIT
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default 1 if !64BIT
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help
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This option determines the size of UML kernel stacks. They will
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be 1 << order pages. The default is OK unless you're running Valgrind
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on UML, in which case, set this to 3.
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It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
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older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
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increase in the size of the state which needs to be saved when handling
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signals.
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config MMAPPER
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tristate "iomem emulation driver"
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help
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This driver allows a host file to be used as emulated IO memory inside
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UML.
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config PGTABLE_LEVELS
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int
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default 3 if 3_LEVEL_PGTABLES
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default 2
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config UML_TIME_TRAVEL_SUPPORT
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bool
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prompt "Support time-travel mode (e.g. for test execution)"
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# inf-cpu mode is incompatible with the benchmarking
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depends on !RAID6_PQ_BENCHMARK
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depends on !SMP
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help
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Enable this option to support time travel inside the UML instance.
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After enabling this option, two modes are accessible at runtime
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(selected by the kernel command line), see the kernel's command-
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line help for more details.
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It is safe to say Y, but you probably don't need this.
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config KASAN_SHADOW_OFFSET
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hex
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depends on KASAN
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default 0x100000000000
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help
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This is the offset at which the ~16TB of shadow memory is
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mapped and used by KASAN for memory debugging. This can be any
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address that has at least KASAN_SHADOW_SIZE (total address space divided
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by 8) amount of space so that the KASAN shadow memory does not conflict
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with anything. The default is 0x100000000000, which works even if mem is
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set to a large value. On low-memory systems, try 0x7fff8000, as it fits
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into the immediate of most instructions, improving performance.
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endmenu
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source "arch/um/drivers/Kconfig"
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config ARCH_SUSPEND_POSSIBLE
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def_bool y
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source "kernel/power/Kconfig"
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