xref: /openbmc/linux/arch/um/Kconfig (revision c358f538)
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
32config MMU
33	bool
34	default y
35
36config UML_DMA_EMULATION
37	bool
38
39config NO_IOMEM
40	bool "disable IOMEM" if EXPERT
41	depends on !INDIRECT_IOMEM
42	default y
43
44config UML_IOMEM_EMULATION
45	bool
46	select INDIRECT_IOMEM
47	select GENERIC_PCI_IOMAP
48	select GENERIC_IOMAP
49	select NO_GENERIC_PCI_IOPORT_MAP
50
51config NO_IOPORT_MAP
52	def_bool y
53
54config ISA
55	bool
56
57config SBUS
58	bool
59
60config LOCKDEP_SUPPORT
61	bool
62	default y
63
64config STACKTRACE_SUPPORT
65	bool
66	default y
67	select STACKTRACE
68
69config GENERIC_CALIBRATE_DELAY
70	bool
71	default y
72
73config HZ
74	int
75	default 100
76
77config NR_CPUS
78	int
79	range 1 1
80	default 1
81
82config ARCH_HAS_CACHE_LINE_SIZE
83	def_bool y
84
85source "arch/$(HEADER_ARCH)/um/Kconfig"
86
87config MAY_HAVE_RUNTIME_DEPS
88	bool
89
90config STATIC_LINK
91	bool "Force a static link"
92	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
93	help
94	  This option gives you the ability to force a static link of UML.
95	  Normally, UML is linked as a shared binary.  This is inconvenient for
96	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
97	  you probably want to say Y here.
98	  Additionally, this option enables using higher memory spaces (up to
99	  2.75G) for UML.
100
101	  NOTE: This option is incompatible with some networking features which
102	  depend on features that require being dynamically loaded (like NSS).
103
104config LD_SCRIPT_STATIC
105	bool
106	default y
107	depends on STATIC_LINK
108
109config LD_SCRIPT_DYN
110	bool
111	default y
112	depends on !LD_SCRIPT_STATIC
113
114config LD_SCRIPT_DYN_RPATH
115	bool "set rpath in the binary" if EXPERT
116	default y
117	depends on LD_SCRIPT_DYN
118	help
119	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
120	  explicitly.
121
122	  You may need to turn this off if compiling for nix systems
123	  that have their libraries in random /nix directories and
124	  might otherwise unexpected use libraries from /lib or /lib64
125	  instead of the desired ones.
126
127config HOSTFS
128	tristate "Host filesystem"
129	help
130	  While the User-Mode Linux port uses its own root file system for
131	  booting and normal file access, this module lets the UML user
132	  access files stored on the host.  It does not require any
133	  network connection between the Host and UML.  An example use of
134	  this might be:
135
136	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
137
138	  where /tmp/fromhost is an empty directory inside UML and
139	  /tmp/umlshare is a directory on the host with files the UML user
140	  wishes to access.
141
142	  For more information, see
143	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
144
145	  If you'd like to be able to work with files stored on the host,
146	  say Y or M here; otherwise say N.
147
148config MCONSOLE
149	bool "Management console"
150	depends on PROC_FS
151	default y
152	help
153	  The user mode linux management console is a low-level interface to
154	  the kernel, somewhat like the i386 SysRq interface.  Since there is
155	  a full-blown operating system running under every user mode linux
156	  instance, there is much greater flexibility possible than with the
157	  SysRq mechanism.
158
159	  If you answer 'Y' to this option, to use this feature, you need the
160	  mconsole client (called uml_mconsole) which is present in CVS in
161	  2.4.5-9um and later (path /tools/mconsole), and is also in the
162	  distribution RPM package in 2.4.6 and later.
163
164	  It is safe to say 'Y' here.
165
166config MAGIC_SYSRQ
167	bool "Magic SysRq key"
168	depends on MCONSOLE
169	help
170	  If you say Y here, you will have some control over the system even
171	  if the system crashes for example during kernel debugging (e.g., you
172	  will be able to flush the buffer cache to disk, reboot the system
173	  immediately or dump some status information). A key for each of the
174	  possible requests is provided.
175
176	  This is the feature normally accomplished by pressing a key
177	  while holding SysRq (Alt+PrintScreen).
178
179	  On UML, this is accomplished by sending a "sysrq" command with
180	  mconsole, followed by the letter for the requested command.
181
182	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
183	  unless you really know what this hack does.
184
185config KERNEL_STACK_ORDER
186	int "Kernel stack size order"
187	default 2 if 64BIT
188	range 2 10 if 64BIT
189	default 1 if !64BIT
190	help
191	  This option determines the size of UML kernel stacks.  They will
192	  be 1 << order pages.  The default is OK unless you're running Valgrind
193	  on UML, in which case, set this to 3.
194	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
195	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
196	  increase in the size of the state which needs to be saved when handling
197	  signals.
198
199config MMAPPER
200	tristate "iomem emulation driver"
201	help
202	  This driver allows a host file to be used as emulated IO memory inside
203	  UML.
204
205config PGTABLE_LEVELS
206	int
207	default 3 if 3_LEVEL_PGTABLES
208	default 2
209
210config UML_TIME_TRAVEL_SUPPORT
211	bool
212	prompt "Support time-travel mode (e.g. for test execution)"
213	# inf-cpu mode is incompatible with the benchmarking
214	depends on !RAID6_PQ_BENCHMARK
215	depends on !SMP
216	help
217	  Enable this option to support time travel inside the UML instance.
218
219	  After enabling this option, two modes are accessible at runtime
220	  (selected by the kernel command line), see the kernel's command-
221	  line help for more details.
222
223	  It is safe to say Y, but you probably don't need this.
224
225config KASAN_SHADOW_OFFSET
226	hex
227	depends on KASAN
228	default 0x100000000000
229	help
230	  This is the offset at which the ~16TB of shadow memory is
231	  mapped and used by KASAN for memory debugging. This can be any
232	  address that has at least KASAN_SHADOW_SIZE (total address space divided
233	  by 8) amount of space so that the KASAN shadow memory does not conflict
234	  with anything. The default is 0x100000000000, which works even if mem is
235	  set to a large value. On low-memory systems, try 0x7fff8000, as it fits
236	  into the immediate of most instructions, improving performance.
237
238endmenu
239
240source "arch/um/drivers/Kconfig"
241
242config ARCH_SUSPEND_POSSIBLE
243	def_bool y
244
245source "kernel/power/Kconfig"
246