xref: /linux/arch/um/Kconfig (revision cbac924200b838cfb8d8b1415113d788089dc50b) 
1# SPDX-License-Identifier: GPL-2.0
2
3menu "UML-specific options"
4
5config UML
6	bool
7	default y
8	select ARCH_EPHEMERAL_INODES
9	select ARCH_HAS_KCOV
10	select ARCH_HAS_STRNCPY_FROM_USER
11	select ARCH_HAS_STRNLEN_USER
12	select ARCH_NO_PREEMPT
13	select HAVE_ARCH_AUDITSYSCALL
14	select HAVE_ARCH_SECCOMP_FILTER
15	select HAVE_ASM_MODVERSIONS
16	select HAVE_UID16
17	select HAVE_DEBUG_KMEMLEAK
18	select HAVE_DEBUG_BUGVERBOSE
19	select NO_DMA if !UML_DMA_EMULATION
20	select OF_EARLY_FLATTREE if OF
21	select GENERIC_IRQ_SHOW
22	select GENERIC_CPU_DEVICES
23	select HAVE_GCC_PLUGINS
24	select TRACE_IRQFLAGS_SUPPORT
25	select TTY # Needed for line.c
26	select HAVE_ARCH_VMAP_STACK
27
28config MMU
29	bool
30	default y
31
32config UML_DMA_EMULATION
33	bool
34
35config NO_IOMEM
36	bool "disable IOMEM" if EXPERT
37	depends on !INDIRECT_IOMEM
38	default y
39
40config UML_IOMEM_EMULATION
41	bool
42	select INDIRECT_IOMEM
43	select GENERIC_PCI_IOMAP
44	select GENERIC_IOMAP
45	select NO_GENERIC_PCI_IOPORT_MAP
46
47config NO_IOPORT_MAP
48	def_bool y
49
50config ISA
51	bool
52
53config SBUS
54	bool
55
56config LOCKDEP_SUPPORT
57	bool
58	default y
59
60config STACKTRACE_SUPPORT
61	bool
62	default y
63	select STACKTRACE
64
65config GENERIC_CALIBRATE_DELAY
66	bool
67	default y
68
69config HZ
70	int
71	default 100
72
73config NR_CPUS
74	int
75	range 1 1
76	default 1
77
78config ARCH_HAS_CACHE_LINE_SIZE
79	def_bool y
80
81source "arch/$(HEADER_ARCH)/um/Kconfig"
82
83config MAY_HAVE_RUNTIME_DEPS
84        bool
85
86config STATIC_LINK
87	bool "Force a static link"
88	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
89	help
90	  This option gives you the ability to force a static link of UML.
91	  Normally, UML is linked as a shared binary.  This is inconvenient for
92	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
93	  you probably want to say Y here.
94	  Additionally, this option enables using higher memory spaces (up to
95	  2.75G) for UML.
96
97	  NOTE: This option is incompatible with some networking features which
98	  depend on features that require being dynamically loaded (like NSS).
99
100config LD_SCRIPT_STATIC
101	bool
102	default y
103	depends on STATIC_LINK
104
105config LD_SCRIPT_DYN
106	bool
107	default y
108	depends on !LD_SCRIPT_STATIC
109	select MODULE_REL_CRCS if MODVERSIONS
110
111config LD_SCRIPT_DYN_RPATH
112	bool "set rpath in the binary" if EXPERT
113	default y
114	depends on LD_SCRIPT_DYN
115	help
116	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
117	  explicitly.
118
119	  You may need to turn this off if compiling for nix systems
120	  that have their libraries in random /nix directories and
121	  might otherwise unexpected use libraries from /lib or /lib64
122	  instead of the desired ones.
123
124config HOSTFS
125	tristate "Host filesystem"
126	help
127	  While the User-Mode Linux port uses its own root file system for
128	  booting and normal file access, this module lets the UML user
129	  access files stored on the host.  It does not require any
130	  network connection between the Host and UML.  An example use of
131	  this might be:
132
133	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
134
135	  where /tmp/fromhost is an empty directory inside UML and
136	  /tmp/umlshare is a directory on the host with files the UML user
137	  wishes to access.
138
139	  For more information, see
140	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
141
142	  If you'd like to be able to work with files stored on the host,
143	  say Y or M here; otherwise say N.
144
145config MCONSOLE
146	bool "Management console"
147	depends on PROC_FS
148	default y
149	help
150	  The user mode linux management console is a low-level interface to
151	  the kernel, somewhat like the i386 SysRq interface.  Since there is
152	  a full-blown operating system running under every user mode linux
153	  instance, there is much greater flexibility possible than with the
154	  SysRq mechanism.
155
156	  If you answer 'Y' to this option, to use this feature, you need the
157	  mconsole client (called uml_mconsole) which is present in CVS in
158	  2.4.5-9um and later (path /tools/mconsole), and is also in the
159	  distribution RPM package in 2.4.6 and later.
160
161	  It is safe to say 'Y' here.
162
163config MAGIC_SYSRQ
164	bool "Magic SysRq key"
165	depends on MCONSOLE
166	help
167	  If you say Y here, you will have some control over the system even
168	  if the system crashes for example during kernel debugging (e.g., you
169	  will be able to flush the buffer cache to disk, reboot the system
170	  immediately or dump some status information). A key for each of the
171	  possible requests is provided.
172
173	  This is the feature normally accomplished by pressing a key
174	  while holding SysRq (Alt+PrintScreen).
175
176	  On UML, this is accomplished by sending a "sysrq" command with
177	  mconsole, followed by the letter for the requested command.
178
179	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
180	  unless you really know what this hack does.
181
182config KERNEL_STACK_ORDER
183	int "Kernel stack size order"
184	default 2 if 64BIT
185	range 2 10 if 64BIT
186	default 1 if !64BIT
187	help
188	  This option determines the size of UML kernel stacks.  They will
189	  be 1 << order pages.  The default is OK unless you're running Valgrind
190	  on UML, in which case, set this to 3.
191	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
192	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
193	  increase in the size of the state which needs to be saved when handling
194	  signals.
195
196config MMAPPER
197	tristate "iomem emulation driver"
198	help
199	  This driver allows a host file to be used as emulated IO memory inside
200	  UML.
201
202config PGTABLE_LEVELS
203	int
204	default 3 if 3_LEVEL_PGTABLES
205	default 2
206
207config UML_TIME_TRAVEL_SUPPORT
208	bool
209	prompt "Support time-travel mode (e.g. for test execution)"
210	# inf-cpu mode is incompatible with the benchmarking
211	depends on !RAID6_PQ_BENCHMARK
212	depends on !SMP
213	help
214	  Enable this option to support time travel inside the UML instance.
215
216	  After enabling this option, two modes are accessible at runtime
217	  (selected by the kernel command line), see the kernel's command-
218	  line help for more details.
219
220	  It is safe to say Y, but you probably don't need this.
221
222endmenu
223
224source "arch/um/drivers/Kconfig"
225
226config ARCH_SUSPEND_POSSIBLE
227	def_bool y
228
229source "kernel/power/Kconfig"
230