xref: /linux/arch/um/Kconfig (revision db10cb9b) 
1# SPDX-License-Identifier: GPL-2.0
2
3menu "UML-specific options"
4
5config UML
6	bool
7	default y
8	select ARCH_HAS_CPU_FINALIZE_INIT
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 ARCH_SUPPORTS_LTO_CLANG
29	select ARCH_SUPPORTS_LTO_CLANG_THIN
30	select TRACE_IRQFLAGS_SUPPORT
31	select TTY # Needed for line.c
32	select HAVE_ARCH_VMAP_STACK
33	select HAVE_RUST			if X86_64
34
35config MMU
36	bool
37	default y
38
39config UML_DMA_EMULATION
40	bool
41
42config NO_IOMEM
43	bool "disable IOMEM" if EXPERT
44	depends on !INDIRECT_IOMEM
45	default y
46
47config UML_IOMEM_EMULATION
48	bool
49	select INDIRECT_IOMEM
50	select GENERIC_PCI_IOMAP
51	select GENERIC_IOMAP
52	select NO_GENERIC_PCI_IOPORT_MAP
53
54config NO_IOPORT_MAP
55	def_bool y
56
57config ISA
58	bool
59
60config SBUS
61	bool
62
63config LOCKDEP_SUPPORT
64	bool
65	default y
66
67config STACKTRACE_SUPPORT
68	bool
69	default y
70	select STACKTRACE
71
72config GENERIC_CALIBRATE_DELAY
73	bool
74	default y
75
76config HZ
77	int
78	default 100
79
80config NR_CPUS
81	int
82	range 1 1
83	default 1
84
85config ARCH_HAS_CACHE_LINE_SIZE
86	def_bool y
87
88source "arch/$(HEADER_ARCH)/um/Kconfig"
89
90config MAY_HAVE_RUNTIME_DEPS
91	bool
92
93config STATIC_LINK
94	bool "Force a static link"
95	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
96	help
97	  This option gives you the ability to force a static link of UML.
98	  Normally, UML is linked as a shared binary.  This is inconvenient for
99	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
100	  you probably want to say Y here.
101	  Additionally, this option enables using higher memory spaces (up to
102	  2.75G) for UML.
103
104	  NOTE: This option is incompatible with some networking features which
105	  depend on features that require being dynamically loaded (like NSS).
106
107config LD_SCRIPT_STATIC
108	bool
109	default y
110	depends on STATIC_LINK
111
112config LD_SCRIPT_DYN
113	bool
114	default y
115	depends on !LD_SCRIPT_STATIC
116
117config LD_SCRIPT_DYN_RPATH
118	bool "set rpath in the binary" if EXPERT
119	default y
120	depends on LD_SCRIPT_DYN
121	help
122	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
123	  explicitly.
124
125	  You may need to turn this off if compiling for nix systems
126	  that have their libraries in random /nix directories and
127	  might otherwise unexpected use libraries from /lib or /lib64
128	  instead of the desired ones.
129
130config HOSTFS
131	tristate "Host filesystem"
132	help
133	  While the User-Mode Linux port uses its own root file system for
134	  booting and normal file access, this module lets the UML user
135	  access files stored on the host.  It does not require any
136	  network connection between the Host and UML.  An example use of
137	  this might be:
138
139	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
140
141	  where /tmp/fromhost is an empty directory inside UML and
142	  /tmp/umlshare is a directory on the host with files the UML user
143	  wishes to access.
144
145	  For more information, see
146	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
147
148	  If you'd like to be able to work with files stored on the host,
149	  say Y or M here; otherwise say N.
150
151config MCONSOLE
152	bool "Management console"
153	depends on PROC_FS
154	default y
155	help
156	  The user mode linux management console is a low-level interface to
157	  the kernel, somewhat like the i386 SysRq interface.  Since there is
158	  a full-blown operating system running under every user mode linux
159	  instance, there is much greater flexibility possible than with the
160	  SysRq mechanism.
161
162	  If you answer 'Y' to this option, to use this feature, you need the
163	  mconsole client (called uml_mconsole) which is present in CVS in
164	  2.4.5-9um and later (path /tools/mconsole), and is also in the
165	  distribution RPM package in 2.4.6 and later.
166
167	  It is safe to say 'Y' here.
168
169config MAGIC_SYSRQ
170	bool "Magic SysRq key"
171	depends on MCONSOLE
172	help
173	  If you say Y here, you will have some control over the system even
174	  if the system crashes for example during kernel debugging (e.g., you
175	  will be able to flush the buffer cache to disk, reboot the system
176	  immediately or dump some status information). A key for each of the
177	  possible requests is provided.
178
179	  This is the feature normally accomplished by pressing a key
180	  while holding SysRq (Alt+PrintScreen).
181
182	  On UML, this is accomplished by sending a "sysrq" command with
183	  mconsole, followed by the letter for the requested command.
184
185	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
186	  unless you really know what this hack does.
187
188config KERNEL_STACK_ORDER
189	int "Kernel stack size order"
190	default 2 if 64BIT
191	range 2 10 if 64BIT
192	default 1 if !64BIT
193	help
194	  This option determines the size of UML kernel stacks.  They will
195	  be 1 << order pages.  The default is OK unless you're running Valgrind
196	  on UML, in which case, set this to 3.
197	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
198	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
199	  increase in the size of the state which needs to be saved when handling
200	  signals.
201
202config MMAPPER
203	tristate "iomem emulation driver"
204	help
205	  This driver allows a host file to be used as emulated IO memory inside
206	  UML.
207
208config PGTABLE_LEVELS
209	int
210	default 3 if 3_LEVEL_PGTABLES
211	default 2
212
213config UML_TIME_TRAVEL_SUPPORT
214	bool
215	prompt "Support time-travel mode (e.g. for test execution)"
216	# inf-cpu mode is incompatible with the benchmarking
217	depends on !RAID6_PQ_BENCHMARK
218	depends on !SMP
219	help
220	  Enable this option to support time travel inside the UML instance.
221
222	  After enabling this option, two modes are accessible at runtime
223	  (selected by the kernel command line), see the kernel's command-
224	  line help for more details.
225
226	  It is safe to say Y, but you probably don't need this.
227
228config KASAN_SHADOW_OFFSET
229	hex
230	depends on KASAN
231	default 0x100000000000
232	help
233	  This is the offset at which the ~16TB of shadow memory is
234	  mapped and used by KASAN for memory debugging. This can be any
235	  address that has at least KASAN_SHADOW_SIZE (total address space divided
236	  by 8) amount of space so that the KASAN shadow memory does not conflict
237	  with anything. The default is 0x100000000000, which works even if mem is
238	  set to a large value. On low-memory systems, try 0x7fff8000, as it fits
239	  into the immediate of most instructions, improving performance.
240
241endmenu
242
243source "arch/um/drivers/Kconfig"
244
245config ARCH_SUSPEND_POSSIBLE
246	def_bool y
247
248menu "Power management options"
249
250source "kernel/power/Kconfig"
251
252endmenu
253