xref: /linux/arch/um/Kconfig (revision f09c3fcf) 
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_FORTIFY_SOURCE
10	select ARCH_HAS_GCOV_PROFILE_ALL
11	select ARCH_HAS_KCOV
12	select ARCH_HAS_STRNCPY_FROM_USER
13	select ARCH_HAS_STRNLEN_USER
14	select ARCH_NO_PREEMPT
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 NO_DMA if !UML_DMA_EMULATION
24	select OF_EARLY_FLATTREE if OF
25	select GENERIC_IRQ_SHOW
26	select GENERIC_CPU_DEVICES
27	select HAVE_GCC_PLUGINS
28	select TRACE_IRQFLAGS_SUPPORT
29	select TTY # Needed for line.c
30	select HAVE_ARCH_VMAP_STACK
31	select HAVE_RUST			if X86_64
32
33config MMU
34	bool
35	default y
36
37config UML_DMA_EMULATION
38	bool
39
40config NO_IOMEM
41	bool "disable IOMEM" if EXPERT
42	depends on !INDIRECT_IOMEM
43	default y
44
45config UML_IOMEM_EMULATION
46	bool
47	select INDIRECT_IOMEM
48	select GENERIC_PCI_IOMAP
49	select GENERIC_IOMAP
50	select NO_GENERIC_PCI_IOPORT_MAP
51
52config NO_IOPORT_MAP
53	def_bool y
54
55config ISA
56	bool
57
58config SBUS
59	bool
60
61config LOCKDEP_SUPPORT
62	bool
63	default y
64
65config STACKTRACE_SUPPORT
66	bool
67	default y
68	select STACKTRACE
69
70config GENERIC_CALIBRATE_DELAY
71	bool
72	default y
73
74config HZ
75	int
76	default 100
77
78config NR_CPUS
79	int
80	range 1 1
81	default 1
82
83config ARCH_HAS_CACHE_LINE_SIZE
84	def_bool y
85
86source "arch/$(HEADER_ARCH)/um/Kconfig"
87
88config MAY_HAVE_RUNTIME_DEPS
89	bool
90
91config STATIC_LINK
92	bool "Force a static link"
93	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
94	help
95	  This option gives you the ability to force a static link of UML.
96	  Normally, UML is linked as a shared binary.  This is inconvenient for
97	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
98	  you probably want to say Y here.
99	  Additionally, this option enables using higher memory spaces (up to
100	  2.75G) for UML.
101
102	  NOTE: This option is incompatible with some networking features which
103	  depend on features that require being dynamically loaded (like NSS).
104
105config LD_SCRIPT_STATIC
106	bool
107	default y
108	depends on STATIC_LINK
109
110config LD_SCRIPT_DYN
111	bool
112	default y
113	depends on !LD_SCRIPT_STATIC
114
115config LD_SCRIPT_DYN_RPATH
116	bool "set rpath in the binary" if EXPERT
117	default y
118	depends on LD_SCRIPT_DYN
119	help
120	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
121	  explicitly.
122
123	  You may need to turn this off if compiling for nix systems
124	  that have their libraries in random /nix directories and
125	  might otherwise unexpected use libraries from /lib or /lib64
126	  instead of the desired ones.
127
128config HOSTFS
129	tristate "Host filesystem"
130	help
131	  While the User-Mode Linux port uses its own root file system for
132	  booting and normal file access, this module lets the UML user
133	  access files stored on the host.  It does not require any
134	  network connection between the Host and UML.  An example use of
135	  this might be:
136
137	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
138
139	  where /tmp/fromhost is an empty directory inside UML and
140	  /tmp/umlshare is a directory on the host with files the UML user
141	  wishes to access.
142
143	  For more information, see
144	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
145
146	  If you'd like to be able to work with files stored on the host,
147	  say Y or M here; otherwise say N.
148
149config MCONSOLE
150	bool "Management console"
151	depends on PROC_FS
152	default y
153	help
154	  The user mode linux management console is a low-level interface to
155	  the kernel, somewhat like the i386 SysRq interface.  Since there is
156	  a full-blown operating system running under every user mode linux
157	  instance, there is much greater flexibility possible than with the
158	  SysRq mechanism.
159
160	  If you answer 'Y' to this option, to use this feature, you need the
161	  mconsole client (called uml_mconsole) which is present in CVS in
162	  2.4.5-9um and later (path /tools/mconsole), and is also in the
163	  distribution RPM package in 2.4.6 and later.
164
165	  It is safe to say 'Y' here.
166
167config MAGIC_SYSRQ
168	bool "Magic SysRq key"
169	depends on MCONSOLE
170	help
171	  If you say Y here, you will have some control over the system even
172	  if the system crashes for example during kernel debugging (e.g., you
173	  will be able to flush the buffer cache to disk, reboot the system
174	  immediately or dump some status information). A key for each of the
175	  possible requests is provided.
176
177	  This is the feature normally accomplished by pressing a key
178	  while holding SysRq (Alt+PrintScreen).
179
180	  On UML, this is accomplished by sending a "sysrq" command with
181	  mconsole, followed by the letter for the requested command.
182
183	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
184	  unless you really know what this hack does.
185
186config KERNEL_STACK_ORDER
187	int "Kernel stack size order"
188	default 2 if 64BIT
189	range 2 10 if 64BIT
190	default 1 if !64BIT
191	help
192	  This option determines the size of UML kernel stacks.  They will
193	  be 1 << order pages.  The default is OK unless you're running Valgrind
194	  on UML, in which case, set this to 3.
195	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
196	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
197	  increase in the size of the state which needs to be saved when handling
198	  signals.
199
200config MMAPPER
201	tristate "iomem emulation driver"
202	help
203	  This driver allows a host file to be used as emulated IO memory inside
204	  UML.
205
206config PGTABLE_LEVELS
207	int
208	default 3 if 3_LEVEL_PGTABLES
209	default 2
210
211config UML_TIME_TRAVEL_SUPPORT
212	bool
213	prompt "Support time-travel mode (e.g. for test execution)"
214	# inf-cpu mode is incompatible with the benchmarking
215	depends on !RAID6_PQ_BENCHMARK
216	depends on !SMP
217	help
218	  Enable this option to support time travel inside the UML instance.
219
220	  After enabling this option, two modes are accessible at runtime
221	  (selected by the kernel command line), see the kernel's command-
222	  line help for more details.
223
224	  It is safe to say Y, but you probably don't need this.
225
226config KASAN_SHADOW_OFFSET
227	hex
228	depends on KASAN
229	default 0x100000000000
230	help
231	  This is the offset at which the ~16TB of shadow memory is
232	  mapped and used by KASAN for memory debugging. This can be any
233	  address that has at least KASAN_SHADOW_SIZE (total address space divided
234	  by 8) amount of space so that the KASAN shadow memory does not conflict
235	  with anything. The default is 0x100000000000, which works even if mem is
236	  set to a large value. On low-memory systems, try 0x7fff8000, as it fits
237	  into the immediate of most instructions, improving performance.
238
239endmenu
240
241source "arch/um/drivers/Kconfig"
242
243config ARCH_SUSPEND_POSSIBLE
244	def_bool y
245
246menu "Power management options"
247
248source "kernel/power/Kconfig"
249
250endmenu
251