# 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_HAS_KCOV
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select ARCH_NO_PREEMPT
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select HAVE_ARCH_AUDITSYSCALL
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select HAVE_ARCH_SECCOMP_FILTER
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select HAVE_UID16
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select HAVE_FUTEX_CMPXCHG if FUTEX
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select HAVE_DEBUG_KMEMLEAK
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select GENERIC_IRQ_SHOW
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select GENERIC_CPU_DEVICES
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select GENERIC_CLOCKEVENTS
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select HAVE_GCC_PLUGINS
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select TTY # Needed for line.c
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config MMU
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bool
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default y
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config NO_IOMEM
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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 PCI
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bool
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config PCMCIA
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bool
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config TRACE_IRQFLAGS_SUPPORT
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bool
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default y
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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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source "arch/$(HEADER_ARCH)/um/Kconfig"
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config STATIC_LINK
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bool "Force a static link"
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default n
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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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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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select MODULE_REL_CRCS if MODVERSIONS
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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 1 if 64BIT
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range 1 10 if 64BIT
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default 0 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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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 NO_DMA
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def_bool y
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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 SECCOMP
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def_bool y
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prompt "Enable seccomp to safely compute untrusted bytecode"
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---help---
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This kernel feature is useful for number crunching applications
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that may need to compute untrusted bytecode during their
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execution. By using pipes or other transports made available to
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the process as file descriptors supporting the read/write
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syscalls, it's possible to isolate those applications in
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their own address space using seccomp. Once seccomp is
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enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
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and the task is only allowed to execute a few safe syscalls
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defined by each seccomp mode.
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If unsure, say Y.
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endmenu
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source "arch/um/drivers/Kconfig"
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