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1# SPDX-License-Identifier: GPL-2.0
2
3menu "UML-specific options"
4
5config UML
6 bool
7 default y
8 select ARCH_HAS_KCOV
9 select ARCH_NO_PREEMPT
10 select HAVE_ARCH_AUDITSYSCALL
11 select HAVE_ARCH_SECCOMP_FILTER
12 select HAVE_ASM_MODVERSIONS
13 select HAVE_UID16
14 select HAVE_FUTEX_CMPXCHG if FUTEX
15 select HAVE_DEBUG_KMEMLEAK
16 select HAVE_DEBUG_BUGVERBOSE
17 select NO_DMA
18 select GENERIC_IRQ_SHOW
19 select GENERIC_CPU_DEVICES
20 select GENERIC_CLOCKEVENTS
21 select HAVE_GCC_PLUGINS
22 select TTY # Needed for line.c
23
24config MMU
25 bool
26 default y
27
28config NO_IOMEM
29 def_bool y
30
31config ISA
32 bool
33
34config SBUS
35 bool
36
37config TRACE_IRQFLAGS_SUPPORT
38 bool
39 default y
40
41config LOCKDEP_SUPPORT
42 bool
43 default y
44
45config STACKTRACE_SUPPORT
46 bool
47 default y
48 select STACKTRACE
49
50config GENERIC_CALIBRATE_DELAY
51 bool
52 default y
53
54config HZ
55 int
56 default 100
57
58config NR_CPUS
59 int
60 range 1 1
61 default 1
62
63source "arch/$(HEADER_ARCH)/um/Kconfig"
64
65config FORBID_STATIC_LINK
66 bool
67
68config STATIC_LINK
69 bool "Force a static link"
70 depends on !FORBID_STATIC_LINK
71 help
72 This option gives you the ability to force a static link of UML.
73 Normally, UML is linked as a shared binary. This is inconvenient for
74 use in a chroot jail. So, if you intend to run UML inside a chroot,
75 you probably want to say Y here.
76 Additionally, this option enables using higher memory spaces (up to
77 2.75G) for UML.
78
79 NOTE: This option is incompatible with some networking features which
80 depend on features that require being dynamically loaded (like NSS).
81
82config LD_SCRIPT_STATIC
83 bool
84 default y
85 depends on STATIC_LINK
86
87config LD_SCRIPT_DYN
88 bool
89 default y
90 depends on !LD_SCRIPT_STATIC
91 select MODULE_REL_CRCS if MODVERSIONS
92
93config HOSTFS
94 tristate "Host filesystem"
95 help
96 While the User-Mode Linux port uses its own root file system for
97 booting and normal file access, this module lets the UML user
98 access files stored on the host. It does not require any
99 network connection between the Host and UML. An example use of
100 this might be:
101
102 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
103
104 where /tmp/fromhost is an empty directory inside UML and
105 /tmp/umlshare is a directory on the host with files the UML user
106 wishes to access.
107
108 For more information, see
109 <http://user-mode-linux.sourceforge.net/hostfs.html>.
110
111 If you'd like to be able to work with files stored on the host,
112 say Y or M here; otherwise say N.
113
114config MCONSOLE
115 bool "Management console"
116 depends on PROC_FS
117 default y
118 help
119 The user mode linux management console is a low-level interface to
120 the kernel, somewhat like the i386 SysRq interface. Since there is
121 a full-blown operating system running under every user mode linux
122 instance, there is much greater flexibility possible than with the
123 SysRq mechanism.
124
125 If you answer 'Y' to this option, to use this feature, you need the
126 mconsole client (called uml_mconsole) which is present in CVS in
127 2.4.5-9um and later (path /tools/mconsole), and is also in the
128 distribution RPM package in 2.4.6 and later.
129
130 It is safe to say 'Y' here.
131
132config MAGIC_SYSRQ
133 bool "Magic SysRq key"
134 depends on MCONSOLE
135 help
136 If you say Y here, you will have some control over the system even
137 if the system crashes for example during kernel debugging (e.g., you
138 will be able to flush the buffer cache to disk, reboot the system
139 immediately or dump some status information). A key for each of the
140 possible requests is provided.
141
142 This is the feature normally accomplished by pressing a key
143 while holding SysRq (Alt+PrintScreen).
144
145 On UML, this is accomplished by sending a "sysrq" command with
146 mconsole, followed by the letter for the requested command.
147
148 The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
149 unless you really know what this hack does.
150
151config KERNEL_STACK_ORDER
152 int "Kernel stack size order"
153 default 2 if 64BIT
154 range 2 10 if 64BIT
155 default 1 if !64BIT
156 help
157 This option determines the size of UML kernel stacks. They will
158 be 1 << order pages. The default is OK unless you're running Valgrind
159 on UML, in which case, set this to 3.
160 It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
161 older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
162 increase in the size of the state which needs to be saved when handling
163 signals.
164
165config MMAPPER
166 tristate "iomem emulation driver"
167 help
168 This driver allows a host file to be used as emulated IO memory inside
169 UML.
170
171config PGTABLE_LEVELS
172 int
173 default 3 if 3_LEVEL_PGTABLES
174 default 2
175
176config SECCOMP
177 def_bool y
178 prompt "Enable seccomp to safely compute untrusted bytecode"
179 help
180 This kernel feature is useful for number crunching applications
181 that may need to compute untrusted bytecode during their
182 execution. By using pipes or other transports made available to
183 the process as file descriptors supporting the read/write
184 syscalls, it's possible to isolate those applications in
185 their own address space using seccomp. Once seccomp is
186 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
187 and the task is only allowed to execute a few safe syscalls
188 defined by each seccomp mode.
189
190 If unsure, say Y.
191
192config UML_TIME_TRAVEL_SUPPORT
193 bool
194 prompt "Support time-travel mode (e.g. for test execution)"
195 # inf-cpu mode is incompatible with the benchmarking
196 depends on !RAID6_PQ_BENCHMARK
197 depends on !SMP
198 help
199 Enable this option to support time travel inside the UML instance.
200
201 After enabling this option, two modes are accessible at runtime
202 (selected by the kernel command line), see the kernel's command-
203 line help for more details.
204
205 It is safe to say Y, but you probably don't need this.
206
207endmenu
208
209source "arch/um/drivers/Kconfig"
1# SPDX-License-Identifier: GPL-2.0
2
3menu "UML-specific options"
4
5config UML
6 bool
7 default y
8 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
9 select ARCH_HAS_CPU_FINALIZE_INIT
10 select ARCH_HAS_FORTIFY_SOURCE
11 select ARCH_HAS_GCOV_PROFILE_ALL
12 select ARCH_HAS_KCOV
13 select ARCH_HAS_STRNCPY_FROM_USER
14 select ARCH_HAS_STRNLEN_USER
15 select HAVE_ARCH_AUDITSYSCALL
16 select HAVE_ARCH_KASAN if X86_64
17 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
18 select HAVE_ARCH_SECCOMP_FILTER
19 select HAVE_ASM_MODVERSIONS
20 select HAVE_UID16
21 select HAVE_DEBUG_KMEMLEAK
22 select HAVE_DEBUG_BUGVERBOSE
23 select HAVE_PAGE_SIZE_4KB
24 select NO_DMA if !UML_DMA_EMULATION
25 select OF_EARLY_FLATTREE if OF
26 select GENERIC_IRQ_SHOW
27 select GENERIC_CPU_DEVICES
28 select HAVE_GCC_PLUGINS
29 select ARCH_SUPPORTS_LTO_CLANG
30 select ARCH_SUPPORTS_LTO_CLANG_THIN
31 select TRACE_IRQFLAGS_SUPPORT
32 select TTY # Needed for line.c
33 select HAVE_ARCH_VMAP_STACK
34 select HAVE_RUST
35 select ARCH_HAS_UBSAN
36 select HAVE_ARCH_TRACEHOOK
37 select THREAD_INFO_IN_TASK
38
39config MMU
40 bool
41 default y
42
43config UML_DMA_EMULATION
44 bool
45
46config NO_IOMEM
47 bool "disable IOMEM" if EXPERT
48 depends on !INDIRECT_IOMEM
49 default y
50
51config UML_IOMEM_EMULATION
52 bool
53 select INDIRECT_IOMEM
54 select HAS_IOPORT
55 select GENERIC_PCI_IOMAP
56 select GENERIC_IOMAP
57 select NO_GENERIC_PCI_IOPORT_MAP
58
59config NO_IOPORT_MAP
60 def_bool !UML_IOMEM_EMULATION
61
62config ISA
63 bool
64
65config SBUS
66 bool
67
68config LOCKDEP_SUPPORT
69 bool
70 default y
71
72config STACKTRACE_SUPPORT
73 bool
74 default y
75 select STACKTRACE
76
77config GENERIC_CALIBRATE_DELAY
78 bool
79 default y
80
81config HZ
82 int
83 default 100
84
85config NR_CPUS
86 int
87 range 1 1
88 default 1
89
90config ARCH_HAS_CACHE_LINE_SIZE
91 def_bool y
92
93source "arch/$(HEADER_ARCH)/um/Kconfig"
94
95config MAY_HAVE_RUNTIME_DEPS
96 bool
97
98config STATIC_LINK
99 bool "Force a static link"
100 depends on !MAY_HAVE_RUNTIME_DEPS
101 help
102 This option gives you the ability to force a static link of UML.
103 Normally, UML is linked as a shared binary. This is inconvenient for
104 use in a chroot jail. So, if you intend to run UML inside a chroot,
105 you probably want to say Y here.
106 Additionally, this option enables using higher memory spaces (up to
107 2.75G) for UML.
108
109 NOTE: This option is incompatible with some networking features which
110 depend on features that require being dynamically loaded (like NSS).
111
112config LD_SCRIPT_STATIC
113 bool
114 default y
115 depends on STATIC_LINK
116
117config LD_SCRIPT_DYN
118 bool
119 default y
120 depends on !LD_SCRIPT_STATIC
121
122config LD_SCRIPT_DYN_RPATH
123 bool "set rpath in the binary" if EXPERT
124 default y
125 depends on LD_SCRIPT_DYN
126 help
127 Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
128 explicitly.
129
130 You may need to turn this off if compiling for nix systems
131 that have their libraries in random /nix directories and
132 might otherwise unexpected use libraries from /lib or /lib64
133 instead of the desired ones.
134
135config HOSTFS
136 tristate "Host filesystem"
137 help
138 While the User-Mode Linux port uses its own root file system for
139 booting and normal file access, this module lets the UML user
140 access files stored on the host. It does not require any
141 network connection between the Host and UML. An example use of
142 this might be:
143
144 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
145
146 where /tmp/fromhost is an empty directory inside UML and
147 /tmp/umlshare is a directory on the host with files the UML user
148 wishes to access.
149
150 For more information, see
151 <http://user-mode-linux.sourceforge.net/hostfs.html>.
152
153 If you'd like to be able to work with files stored on the host,
154 say Y or M here; otherwise say N.
155
156config MCONSOLE
157 bool "Management console"
158 depends on PROC_FS
159 default y
160 help
161 The user mode linux management console is a low-level interface to
162 the kernel, somewhat like the i386 SysRq interface. Since there is
163 a full-blown operating system running under every user mode linux
164 instance, there is much greater flexibility possible than with the
165 SysRq mechanism.
166
167 If you answer 'Y' to this option, to use this feature, you need the
168 mconsole client (called uml_mconsole) which is present in CVS in
169 2.4.5-9um and later (path /tools/mconsole), and is also in the
170 distribution RPM package in 2.4.6 and later.
171
172 It is safe to say 'Y' here.
173
174config MAGIC_SYSRQ
175 bool "Magic SysRq key"
176 depends on MCONSOLE
177 help
178 If you say Y here, you will have some control over the system even
179 if the system crashes for example during kernel debugging (e.g., you
180 will be able to flush the buffer cache to disk, reboot the system
181 immediately or dump some status information). A key for each of the
182 possible requests is provided.
183
184 This is the feature normally accomplished by pressing a key
185 while holding SysRq (Alt+PrintScreen).
186
187 On UML, this is accomplished by sending a "sysrq" command with
188 mconsole, followed by the letter for the requested command.
189
190 The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
191 unless you really know what this hack does.
192
193config KERNEL_STACK_ORDER
194 int "Kernel stack size order"
195 default 2 if 64BIT
196 range 2 10 if 64BIT
197 default 1 if !64BIT
198 help
199 This option determines the size of UML kernel stacks. They will
200 be 1 << order pages. The default is OK unless you're running Valgrind
201 on UML, in which case, set this to 3.
202 It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
203 older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
204 increase in the size of the state which needs to be saved when handling
205 signals.
206
207config MMAPPER
208 tristate "iomem emulation driver"
209 help
210 This driver allows a host file to be used as emulated IO memory inside
211 UML.
212
213config PGTABLE_LEVELS
214 int
215 default 4 if 64BIT
216 default 2 if !64BIT
217
218config UML_TIME_TRAVEL_SUPPORT
219 bool
220 prompt "Support time-travel mode (e.g. for test execution)"
221 # inf-cpu mode is incompatible with the benchmarking
222 depends on !RAID6_PQ_BENCHMARK
223 depends on !SMP
224 help
225 Enable this option to support time travel inside the UML instance.
226
227 After enabling this option, two modes are accessible at runtime
228 (selected by the kernel command line), see the kernel's command-
229 line help for more details.
230
231 It is safe to say Y, but you probably don't need this.
232
233config UML_MAX_USERSPACE_ITERATIONS
234 int
235 prompt "Maximum number of unscheduled userspace iterations"
236 default 10000
237 depends on UML_TIME_TRAVEL_SUPPORT
238 help
239 In UML inf-cpu and ext time-travel mode userspace can run without being
240 interrupted. This will eventually overwhelm the kernel and create OOM
241 situations (mainly RCU not running). This setting specifies the number
242 of kernel/userspace switches (minor/major page fault, signal or syscall)
243 for the same userspace thread before the sched_clock is advanced by a
244 jiffie to trigger scheduling.
245
246 Setting it to zero disables the feature.
247
248config KASAN_SHADOW_OFFSET
249 hex
250 depends on KASAN
251 default 0x100000000000
252 help
253 This is the offset at which the ~16TB of shadow memory is
254 mapped and used by KASAN for memory debugging. This can be any
255 address that has at least KASAN_SHADOW_SIZE (total address space divided
256 by 8) amount of space so that the KASAN shadow memory does not conflict
257 with anything. The default is 0x100000000000, which works even if mem is
258 set to a large value. On low-memory systems, try 0x7fff8000, as it fits
259 into the immediate of most instructions, improving performance.
260
261endmenu
262
263source "arch/um/drivers/Kconfig"
264
265config ARCH_SUSPEND_POSSIBLE
266 def_bool y
267
268menu "Power management options"
269
270source "kernel/power/Kconfig"
271
272endmenu