1 # SPDX-License-Identifier: GPL-2.0
3 menu "UML-specific options"
8 select ARCH_HAS_CPU_FINALIZE_INIT
10 select ARCH_NO_PREEMPT
11 select HAVE_ARCH_AUDITSYSCALL
12 select HAVE_ARCH_SECCOMP_FILTER
13 select HAVE_ASM_MODVERSIONS
15 select HAVE_FUTEX_CMPXCHG if FUTEX
16 select HAVE_DEBUG_KMEMLEAK
17 select HAVE_DEBUG_BUGVERBOSE
18 select HAVE_COPY_THREAD_TLS
19 select GENERIC_IRQ_SHOW
20 select GENERIC_CPU_DEVICES
21 select GENERIC_CLOCKEVENTS
22 select HAVE_GCC_PLUGINS
23 select TTY # Needed for line.c
38 config TRACE_IRQFLAGS_SUPPORT
42 config LOCKDEP_SUPPORT
46 config STACKTRACE_SUPPORT
51 config GENERIC_CALIBRATE_DELAY
64 source "arch/$(HEADER_ARCH)/um/Kconfig"
67 bool "Force a static link"
70 This option gives you the ability to force a static link of UML.
71 Normally, UML is linked as a shared binary. This is inconvenient for
72 use in a chroot jail. So, if you intend to run UML inside a chroot,
73 you probably want to say Y here.
74 Additionally, this option enables using higher memory spaces (up to
77 config LD_SCRIPT_STATIC
80 depends on STATIC_LINK
85 depends on !LD_SCRIPT_STATIC
86 select MODULE_REL_CRCS if MODVERSIONS
88 config LD_SCRIPT_DYN_RPATH
89 bool "set rpath in the binary" if EXPERT
91 depends on LD_SCRIPT_DYN
93 Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
96 You may need to turn this off if compiling for nix systems
97 that have their libraries in random /nix directories and
98 might otherwise unexpected use libraries from /lib or /lib64
99 instead of the desired ones.
102 tristate "Host filesystem"
104 While the User-Mode Linux port uses its own root file system for
105 booting and normal file access, this module lets the UML user
106 access files stored on the host. It does not require any
107 network connection between the Host and UML. An example use of
110 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
112 where /tmp/fromhost is an empty directory inside UML and
113 /tmp/umlshare is a directory on the host with files the UML user
116 For more information, see
117 <http://user-mode-linux.sourceforge.net/hostfs.html>.
119 If you'd like to be able to work with files stored on the host,
120 say Y or M here; otherwise say N.
123 bool "Management console"
127 The user mode linux management console is a low-level interface to
128 the kernel, somewhat like the i386 SysRq interface. Since there is
129 a full-blown operating system running under every user mode linux
130 instance, there is much greater flexibility possible than with the
133 If you answer 'Y' to this option, to use this feature, you need the
134 mconsole client (called uml_mconsole) which is present in CVS in
135 2.4.5-9um and later (path /tools/mconsole), and is also in the
136 distribution RPM package in 2.4.6 and later.
138 It is safe to say 'Y' here.
141 bool "Magic SysRq key"
144 If you say Y here, you will have some control over the system even
145 if the system crashes for example during kernel debugging (e.g., you
146 will be able to flush the buffer cache to disk, reboot the system
147 immediately or dump some status information). A key for each of the
148 possible requests is provided.
150 This is the feature normally accomplished by pressing a key
151 while holding SysRq (Alt+PrintScreen).
153 On UML, this is accomplished by sending a "sysrq" command with
154 mconsole, followed by the letter for the requested command.
156 The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
157 unless you really know what this hack does.
159 config KERNEL_STACK_ORDER
160 int "Kernel stack size order"
165 This option determines the size of UML kernel stacks. They will
166 be 1 << order pages. The default is OK unless you're running Valgrind
167 on UML, in which case, set this to 3.
168 It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
169 older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
170 increase in the size of the state which needs to be saved when handling
174 tristate "iomem emulation driver"
176 This driver allows a host file to be used as emulated IO memory inside
182 config PGTABLE_LEVELS
184 default 3 if 3_LEVEL_PGTABLES
189 prompt "Enable seccomp to safely compute untrusted bytecode"
191 This kernel feature is useful for number crunching applications
192 that may need to compute untrusted bytecode during their
193 execution. By using pipes or other transports made available to
194 the process as file descriptors supporting the read/write
195 syscalls, it's possible to isolate those applications in
196 their own address space using seccomp. Once seccomp is
197 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
198 and the task is only allowed to execute a few safe syscalls
199 defined by each seccomp mode.
203 config UML_TIME_TRAVEL_SUPPORT
205 prompt "Support time-travel mode (e.g. for test execution)"
207 Enable this option to support time travel inside the UML instance.
209 After enabling this option, two modes are accessible at runtime
210 (selected by the kernel command line), see the kernel's command-
211 line help for more details.
213 It is safe to say Y, but you probably don't need this.
217 source "arch/um/drivers/Kconfig"