xref: /openbmc/linux/arch/um/Kconfig (revision 877d95dc) 
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_GCOV_PROFILE_ALL
10	select ARCH_HAS_KCOV
11	select ARCH_HAS_STRNCPY_FROM_USER
12	select ARCH_HAS_STRNLEN_USER
13	select ARCH_NO_PREEMPT
14	select HAVE_ARCH_AUDITSYSCALL
15	select HAVE_ARCH_KASAN if X86_64
16	select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
17	select HAVE_ARCH_SECCOMP_FILTER
18	select HAVE_ASM_MODVERSIONS
19	select HAVE_UID16
20	select HAVE_DEBUG_KMEMLEAK
21	select HAVE_DEBUG_BUGVERBOSE
22	select NO_DMA if !UML_DMA_EMULATION
23	select OF_EARLY_FLATTREE if OF
24	select GENERIC_IRQ_SHOW
25	select GENERIC_CPU_DEVICES
26	select HAVE_GCC_PLUGINS
27	select TRACE_IRQFLAGS_SUPPORT
28	select TTY # Needed for line.c
29	select HAVE_ARCH_VMAP_STACK
30
31config MMU
32	bool
33	default y
34
35config UML_DMA_EMULATION
36	bool
37
38config NO_IOMEM
39	bool "disable IOMEM" if EXPERT
40	depends on !INDIRECT_IOMEM
41	default y
42
43config UML_IOMEM_EMULATION
44	bool
45	select INDIRECT_IOMEM
46	select GENERIC_PCI_IOMAP
47	select GENERIC_IOMAP
48	select NO_GENERIC_PCI_IOPORT_MAP
49
50config NO_IOPORT_MAP
51	def_bool y
52
53config ISA
54	bool
55
56config SBUS
57	bool
58
59config LOCKDEP_SUPPORT
60	bool
61	default y
62
63config STACKTRACE_SUPPORT
64	bool
65	default y
66	select STACKTRACE
67
68config GENERIC_CALIBRATE_DELAY
69	bool
70	default y
71
72config HZ
73	int
74	default 100
75
76config NR_CPUS
77	int
78	range 1 1
79	default 1
80
81config ARCH_HAS_CACHE_LINE_SIZE
82	def_bool y
83
84source "arch/$(HEADER_ARCH)/um/Kconfig"
85
86config MAY_HAVE_RUNTIME_DEPS
87	bool
88
89config STATIC_LINK
90	bool "Force a static link"
91	depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || !MAY_HAVE_RUNTIME_DEPS
92	help
93	  This option gives you the ability to force a static link of UML.
94	  Normally, UML is linked as a shared binary.  This is inconvenient for
95	  use in a chroot jail.  So, if you intend to run UML inside a chroot,
96	  you probably want to say Y here.
97	  Additionally, this option enables using higher memory spaces (up to
98	  2.75G) for UML.
99
100	  NOTE: This option is incompatible with some networking features which
101	  depend on features that require being dynamically loaded (like NSS).
102
103config LD_SCRIPT_STATIC
104	bool
105	default y
106	depends on STATIC_LINK
107
108config LD_SCRIPT_DYN
109	bool
110	default y
111	depends on !LD_SCRIPT_STATIC
112
113config LD_SCRIPT_DYN_RPATH
114	bool "set rpath in the binary" if EXPERT
115	default y
116	depends on LD_SCRIPT_DYN
117	help
118	  Add /lib (and /lib64 for 64-bit) to the linux binary's rpath
119	  explicitly.
120
121	  You may need to turn this off if compiling for nix systems
122	  that have their libraries in random /nix directories and
123	  might otherwise unexpected use libraries from /lib or /lib64
124	  instead of the desired ones.
125
126config HOSTFS
127	tristate "Host filesystem"
128	help
129	  While the User-Mode Linux port uses its own root file system for
130	  booting and normal file access, this module lets the UML user
131	  access files stored on the host.  It does not require any
132	  network connection between the Host and UML.  An example use of
133	  this might be:
134
135	  mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
136
137	  where /tmp/fromhost is an empty directory inside UML and
138	  /tmp/umlshare is a directory on the host with files the UML user
139	  wishes to access.
140
141	  For more information, see
142	  <http://user-mode-linux.sourceforge.net/hostfs.html>.
143
144	  If you'd like to be able to work with files stored on the host,
145	  say Y or M here; otherwise say N.
146
147config MCONSOLE
148	bool "Management console"
149	depends on PROC_FS
150	default y
151	help
152	  The user mode linux management console is a low-level interface to
153	  the kernel, somewhat like the i386 SysRq interface.  Since there is
154	  a full-blown operating system running under every user mode linux
155	  instance, there is much greater flexibility possible than with the
156	  SysRq mechanism.
157
158	  If you answer 'Y' to this option, to use this feature, you need the
159	  mconsole client (called uml_mconsole) which is present in CVS in
160	  2.4.5-9um and later (path /tools/mconsole), and is also in the
161	  distribution RPM package in 2.4.6 and later.
162
163	  It is safe to say 'Y' here.
164
165config MAGIC_SYSRQ
166	bool "Magic SysRq key"
167	depends on MCONSOLE
168	help
169	  If you say Y here, you will have some control over the system even
170	  if the system crashes for example during kernel debugging (e.g., you
171	  will be able to flush the buffer cache to disk, reboot the system
172	  immediately or dump some status information). A key for each of the
173	  possible requests is provided.
174
175	  This is the feature normally accomplished by pressing a key
176	  while holding SysRq (Alt+PrintScreen).
177
178	  On UML, this is accomplished by sending a "sysrq" command with
179	  mconsole, followed by the letter for the requested command.
180
181	  The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y
182	  unless you really know what this hack does.
183
184config KERNEL_STACK_ORDER
185	int "Kernel stack size order"
186	default 2 if 64BIT
187	range 2 10 if 64BIT
188	default 1 if !64BIT
189	help
190	  This option determines the size of UML kernel stacks.  They will
191	  be 1 << order pages.  The default is OK unless you're running Valgrind
192	  on UML, in which case, set this to 3.
193	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
194	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
195	  increase in the size of the state which needs to be saved when handling
196	  signals.
197
198config MMAPPER
199	tristate "iomem emulation driver"
200	help
201	  This driver allows a host file to be used as emulated IO memory inside
202	  UML.
203
204config PGTABLE_LEVELS
205	int
206	default 3 if 3_LEVEL_PGTABLES
207	default 2
208
209config UML_TIME_TRAVEL_SUPPORT
210	bool
211	prompt "Support time-travel mode (e.g. for test execution)"
212	# inf-cpu mode is incompatible with the benchmarking
213	depends on !RAID6_PQ_BENCHMARK
214	depends on !SMP
215	help
216	  Enable this option to support time travel inside the UML instance.
217
218	  After enabling this option, two modes are accessible at runtime
219	  (selected by the kernel command line), see the kernel's command-
220	  line help for more details.
221
222	  It is safe to say Y, but you probably don't need this.
223
224config KASAN_SHADOW_OFFSET
225	hex
226	depends on KASAN
227	default 0x100000000000
228	help
229	  This is the offset at which the ~16TB of shadow memory is
230	  mapped and used by KASAN for memory debugging. This can be any
231	  address that has at least KASAN_SHADOW_SIZE (total address space divided
232	  by 8) amount of space so that the KASAN shadow memory does not conflict
233	  with anything. The default is 0x100000000000, which works even if mem is
234	  set to a large value. On low-memory systems, try 0x7fff8000, as it fits
235	  into the immediate of most instructions, improving performance.
236
237endmenu
238
239source "arch/um/drivers/Kconfig"
240
241config ARCH_SUSPEND_POSSIBLE
242	def_bool y
243
244source "kernel/power/Kconfig"
245