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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_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 GENERIC_IRQ_SHOW
18 select GENERIC_CPU_DEVICES
19 select GENERIC_CLOCKEVENTS
20 select HAVE_GCC_PLUGINS
21 select TTY # Needed for line.c
22
23config MMU
24 bool
25 default y
26
27config NO_IOMEM
28 def_bool y
29
30config ISA
31 bool
32
33config SBUS
34 bool
35
36config TRACE_IRQFLAGS_SUPPORT
37 bool
38 default y
39
40config LOCKDEP_SUPPORT
41 bool
42 default y
43
44config STACKTRACE_SUPPORT
45 bool
46 default y
47 select STACKTRACE
48
49config GENERIC_CALIBRATE_DELAY
50 bool
51 default y
52
53config HZ
54 int
55 default 100
56
57config NR_CPUS
58 int
59 range 1 1
60 default 1
61
62source "arch/$(HEADER_ARCH)/um/Kconfig"
63
64config STATIC_LINK
65 bool "Force a static link"
66 default n
67 help
68 This option gives you the ability to force a static link of UML.
69 Normally, UML is linked as a shared binary. This is inconvenient for
70 use in a chroot jail. So, if you intend to run UML inside a chroot,
71 you probably want to say Y here.
72 Additionally, this option enables using higher memory spaces (up to
73 2.75G) for UML.
74
75config LD_SCRIPT_STATIC
76 bool
77 default y
78 depends on STATIC_LINK
79
80config LD_SCRIPT_DYN
81 bool
82 default y
83 depends on !LD_SCRIPT_STATIC
84 select MODULE_REL_CRCS if MODVERSIONS
85
86config HOSTFS
87 tristate "Host filesystem"
88 help
89 While the User-Mode Linux port uses its own root file system for
90 booting and normal file access, this module lets the UML user
91 access files stored on the host. It does not require any
92 network connection between the Host and UML. An example use of
93 this might be:
94
95 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
96
97 where /tmp/fromhost is an empty directory inside UML and
98 /tmp/umlshare is a directory on the host with files the UML user
99 wishes to access.
100
101 For more information, see
102 <http://user-mode-linux.sourceforge.net/hostfs.html>.
103
104 If you'd like to be able to work with files stored on the host,
105 say Y or M here; otherwise say N.
106
107config MCONSOLE
108 bool "Management console"
109 depends on PROC_FS
110 default y
111 help
112 The user mode linux management console is a low-level interface to
113 the kernel, somewhat like the i386 SysRq interface. Since there is
114 a full-blown operating system running under every user mode linux
115 instance, there is much greater flexibility possible than with the
116 SysRq mechanism.
117
118 If you answer 'Y' to this option, to use this feature, you need the
119 mconsole client (called uml_mconsole) which is present in CVS in
120 2.4.5-9um and later (path /tools/mconsole), and is also in the
121 distribution RPM package in 2.4.6 and later.
122
123 It is safe to say 'Y' here.
124
125config MAGIC_SYSRQ
126 bool "Magic SysRq key"
127 depends on MCONSOLE
128 help
129 If you say Y here, you will have some control over the system even
130 if the system crashes for example during kernel debugging (e.g., you
131 will be able to flush the buffer cache to disk, reboot the system
132 immediately or dump some status information). A key for each of the
133 possible requests is provided.
134
135 This is the feature normally accomplished by pressing a key
136 while holding SysRq (Alt+PrintScreen).
137
138 On UML, this is accomplished by sending a "sysrq" command with
139 mconsole, followed by the letter for the requested command.
140
141 The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
142 unless you really know what this hack does.
143
144config KERNEL_STACK_ORDER
145 int "Kernel stack size order"
146 default 2 if 64BIT
147 range 2 10 if 64BIT
148 default 1 if !64BIT
149 help
150 This option determines the size of UML kernel stacks. They will
151 be 1 << order pages. The default is OK unless you're running Valgrind
152 on UML, in which case, set this to 3.
153 It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
154 older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
155 increase in the size of the state which needs to be saved when handling
156 signals.
157
158config MMAPPER
159 tristate "iomem emulation driver"
160 help
161 This driver allows a host file to be used as emulated IO memory inside
162 UML.
163
164config NO_DMA
165 def_bool y
166
167config PGTABLE_LEVELS
168 int
169 default 3 if 3_LEVEL_PGTABLES
170 default 2
171
172config SECCOMP
173 def_bool y
174 prompt "Enable seccomp to safely compute untrusted bytecode"
175 ---help---
176 This kernel feature is useful for number crunching applications
177 that may need to compute untrusted bytecode during their
178 execution. By using pipes or other transports made available to
179 the process as file descriptors supporting the read/write
180 syscalls, it's possible to isolate those applications in
181 their own address space using seccomp. Once seccomp is
182 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
183 and the task is only allowed to execute a few safe syscalls
184 defined by each seccomp mode.
185
186 If unsure, say Y.
187
188config UML_TIME_TRAVEL_SUPPORT
189 bool
190 prompt "Support time-travel mode (e.g. for test execution)"
191 help
192 Enable this option to support time travel inside the UML instance.
193
194 After enabling this option, two modes are accessible at runtime
195 (selected by the kernel command line), see the kernel's command-
196 line help for more details.
197
198 It is safe to say Y, but you probably don't need this.
199
200endmenu
201
202source "arch/um/drivers/Kconfig"