xref: /linux/arch/um/Kconfig (revision a11de92523f75a8140cf8eea3ce9b628f7a3cc77) 
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_FUTEX_CMPXCHG if FUTEX
18	select HAVE_DEBUG_KMEMLEAK
19	select HAVE_DEBUG_BUGVERBOSE
20	select NO_DMA if !UML_DMA_EMULATION
21	select GENERIC_IRQ_SHOW
22	select GENERIC_CPU_DEVICES
23	select HAVE_GCC_PLUGINS
24	select SET_FS
25	select TRACE_IRQFLAGS_SUPPORT
26	select TTY # Needed for line.c
27	select HAVE_ARCH_VMAP_STACK
28
29config MMU
30	bool
31	default y
32
33config UML_DMA_EMULATION
34	bool
35
36config NO_IOMEM
37	bool "disable IOMEM" if EXPERT
38	depends on !INDIRECT_IOMEM
39	default y
40
41config UML_IOMEM_EMULATION
42	bool
43	select INDIRECT_IOMEM
44	select GENERIC_PCI_IOMAP
45	select GENERIC_IOMAP
46	select NO_GENERIC_PCI_IOPORT_MAP
47
48config NO_IOPORT_MAP
49	def_bool y
50
51config ISA
52	bool
53
54config SBUS
55	bool
56
57config LOCKDEP_SUPPORT
58	bool
59	default y
60
61config STACKTRACE_SUPPORT
62	bool
63	default y
64	select STACKTRACE
65
66config GENERIC_CALIBRATE_DELAY
67	bool
68	default y
69
70config HZ
71	int
72	default 100
73
74config NR_CPUS
75	int
76	range 1 1
77	default 1
78
79config ARCH_HAS_CACHE_LINE_SIZE
80	def_bool y
81
82source "arch/$(HEADER_ARCH)/um/Kconfig"
83
84config MAY_HAVE_RUNTIME_DEPS
85        bool
86
87config STATIC_LINK
88	bool "Force a static link"
89	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
90	help
91	  This option gives you the ability to force a static link of UML.
92	  Normally, UML is linked as a shared binary.  This is inconvenient for
93	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
94	  you probably want to say Y here.
95	  Additionally, this option enables using higher memory spaces (up to
96	  2.75G) for UML.
97
98	  NOTE: This option is incompatible with some networking features which
99	  depend on features that require being dynamically loaded (like NSS).
100
101config LD_SCRIPT_STATIC
102	bool
103	default y
104	depends on STATIC_LINK
105
106config LD_SCRIPT_DYN
107	bool
108	default y
109	depends on !LD_SCRIPT_STATIC
110	select MODULE_REL_CRCS if MODVERSIONS
111
112config LD_SCRIPT_DYN_RPATH
113	bool "set rpath in the binary" if EXPERT
114	default y
115	depends on LD_SCRIPT_DYN
116	help
117	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
118	  explicitly.
119
120	  You may need to turn this off if compiling for nix systems
121	  that have their libraries in random /nix directories and
122	  might otherwise unexpected use libraries from /lib or /lib64
123	  instead of the desired ones.
124
125config HOSTFS
126	tristate "Host filesystem"
127	help
128	  While the User-Mode Linux port uses its own root file system for
129	  booting and normal file access, this module lets the UML user
130	  access files stored on the host.  It does not require any
131	  network connection between the Host and UML.  An example use of
132	  this might be:
133
134	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
135
136	  where /tmp/fromhost is an empty directory inside UML and
137	  /tmp/umlshare is a directory on the host with files the UML user
138	  wishes to access.
139
140	  For more information, see
141	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
142
143	  If you'd like to be able to work with files stored on the host,
144	  say Y or M here; otherwise say N.
145
146config MCONSOLE
147	bool "Management console"
148	depends on PROC_FS
149	default y
150	help
151	  The user mode linux management console is a low-level interface to
152	  the kernel, somewhat like the i386 SysRq interface.  Since there is
153	  a full-blown operating system running under every user mode linux
154	  instance, there is much greater flexibility possible than with the
155	  SysRq mechanism.
156
157	  If you answer 'Y' to this option, to use this feature, you need the
158	  mconsole client (called uml_mconsole) which is present in CVS in
159	  2.4.5-9um and later (path /tools/mconsole), and is also in the
160	  distribution RPM package in 2.4.6 and later.
161
162	  It is safe to say 'Y' here.
163
164config MAGIC_SYSRQ
165	bool "Magic SysRq key"
166	depends on MCONSOLE
167	help
168	  If you say Y here, you will have some control over the system even
169	  if the system crashes for example during kernel debugging (e.g., you
170	  will be able to flush the buffer cache to disk, reboot the system
171	  immediately or dump some status information). A key for each of the
172	  possible requests is provided.
173
174	  This is the feature normally accomplished by pressing a key
175	  while holding SysRq (Alt+PrintScreen).
176
177	  On UML, this is accomplished by sending a "sysrq" command with
178	  mconsole, followed by the letter for the requested command.
179
180	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
181	  unless you really know what this hack does.
182
183config KERNEL_STACK_ORDER
184	int "Kernel stack size order"
185	default 2 if 64BIT
186	range 2 10 if 64BIT
187	default 1 if !64BIT
188	help
189	  This option determines the size of UML kernel stacks.  They will
190	  be 1 << order pages.  The default is OK unless you're running Valgrind
191	  on UML, in which case, set this to 3.
192	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
193	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
194	  increase in the size of the state which needs to be saved when handling
195	  signals.
196
197config MMAPPER
198	tristate "iomem emulation driver"
199	help
200	  This driver allows a host file to be used as emulated IO memory inside
201	  UML.
202
203config PGTABLE_LEVELS
204	int
205	default 3 if 3_LEVEL_PGTABLES
206	default 2
207
208config UML_TIME_TRAVEL_SUPPORT
209	bool
210	prompt "Support time-travel mode (e.g. for test execution)"
211	# inf-cpu mode is incompatible with the benchmarking
212	depends on !RAID6_PQ_BENCHMARK
213	depends on !SMP
214	help
215	  Enable this option to support time travel inside the UML instance.
216
217	  After enabling this option, two modes are accessible at runtime
218	  (selected by the kernel command line), see the kernel's command-
219	  line help for more details.
220
221	  It is safe to say Y, but you probably don't need this.
222
223endmenu
224
225source "arch/um/drivers/Kconfig"
226
227config ARCH_SUSPEND_POSSIBLE
228	def_bool y
229
230source "kernel/power/Kconfig"
231