1# SPDX-License-Identifier: GPL-2.0 2 3menu "UML-specific options" 4 5config UML 6 bool 7 default y 8 select ARCH_DISABLE_KASAN_INLINE if STATIC_LINK 9 select ARCH_NEEDS_DEFER_KASAN if STATIC_LINK 10 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 11 select ARCH_HAS_CACHE_LINE_SIZE 12 select ARCH_HAS_CPU_FINALIZE_INIT 13 select ARCH_HAS_FORTIFY_SOURCE 14 select ARCH_HAS_GCOV_PROFILE_ALL 15 select ARCH_HAS_KCOV 16 select ARCH_HAS_STRNCPY_FROM_USER 17 select ARCH_HAS_STRNLEN_USER 18 select ARCH_HAS_STRICT_KERNEL_RWX 19 select HAVE_ARCH_AUDITSYSCALL 20 select HAVE_ARCH_KASAN if X86_64 21 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN 22 select HAVE_ARCH_SECCOMP_FILTER 23 select HAVE_ASM_MODVERSIONS 24 select HAVE_UID16 25 select HAVE_DEBUG_KMEMLEAK 26 select HAVE_DEBUG_BUGVERBOSE 27 select HAVE_PAGE_SIZE_4KB 28 select NO_DMA if !UML_DMA_EMULATION 29 select OF_EARLY_FLATTREE if OF 30 select GENERIC_IRQ_SHOW 31 select GENERIC_CPU_DEVICES 32 select GENERIC_SMP_IDLE_THREAD 33 select HAVE_GCC_PLUGINS 34 select ARCH_SUPPORTS_LTO_CLANG 35 select ARCH_SUPPORTS_LTO_CLANG_THIN 36 select TRACE_IRQFLAGS_SUPPORT 37 select TTY # Needed for line.c 38 select HAVE_ARCH_VMAP_STACK 39 select HAVE_RUST 40 select ARCH_HAS_UBSAN 41 select HAVE_ARCH_TRACEHOOK 42 select HAVE_SYSCALL_TRACEPOINTS 43 select THREAD_INFO_IN_TASK 44 select SPARSE_IRQ 45 select MMU_GATHER_RCU_TABLE_FREE 46 47config MMU 48 bool 49 default y 50 51config UML_DMA_EMULATION 52 bool 53 54config NO_IOMEM 55 bool "disable IOMEM" if EXPERT 56 depends on !INDIRECT_IOMEM 57 default y 58 59config UML_IOMEM_EMULATION 60 bool 61 select INDIRECT_IOMEM 62 select GENERIC_PCI_IOMAP 63 64config ISA 65 bool 66 67config SBUS 68 bool 69 70config LOCKDEP_SUPPORT 71 bool 72 default y 73 74config STACKTRACE_SUPPORT 75 bool 76 default y 77 select STACKTRACE 78 79config GENERIC_CALIBRATE_DELAY 80 bool 81 default y 82 83config HZ 84 int 85 default 100 86 87config UML_SUBARCH_SUPPORTS_SMP 88 bool 89 90config SMP 91 bool "Symmetric multi-processing support" 92 default n 93 depends on UML_SUBARCH_SUPPORTS_SMP 94 help 95 This option enables UML SMP support. 96 97 With this enabled, users can tell UML to start multiple virtual 98 processors. Each virtual processor is represented as a separate 99 host thread. 100 101 In UML, kthreads and normal threads (when running in kernel mode) 102 can be scheduled and executed simultaneously on different virtual 103 processors. However, the userspace code of normal threads still 104 runs within their respective single-threaded stubs. 105 106 That is, SMP support is available both within the kernel and 107 across different processes, but remains limited within threads 108 of the same process in userspace. 109 110config NR_CPUS_RANGE_BEGIN 111 int 112 default 1 if !SMP 113 default 2 114 115config NR_CPUS_RANGE_END 116 int 117 default 1 if !SMP 118 default 64 119 120config NR_CPUS_DEFAULT 121 int 122 default 1 if !SMP 123 default 2 124 125config NR_CPUS 126 int "Maximum number of CPUs" if SMP 127 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END 128 default NR_CPUS_DEFAULT 129 130source "arch/$(HEADER_ARCH)/um/Kconfig" 131 132config MAY_HAVE_RUNTIME_DEPS 133 bool 134 135config STATIC_LINK 136 bool "Force a static link" 137 depends on !MAY_HAVE_RUNTIME_DEPS 138 help 139 This option gives you the ability to force a static link of UML. 140 Normally, UML is linked as a shared binary. This is inconvenient for 141 use in a chroot jail. So, if you intend to run UML inside a chroot, 142 you probably want to say Y here. 143 Additionally, this option enables using higher memory spaces (up to 144 2.75G) for UML. 145 146 NOTE: This option is incompatible with some networking features which 147 depend on features that require being dynamically loaded (like NSS). 148 149config LD_SCRIPT_STATIC 150 bool 151 default y 152 depends on STATIC_LINK 153 154config LD_SCRIPT_DYN 155 bool 156 default y 157 depends on !LD_SCRIPT_STATIC 158 159config LD_SCRIPT_DYN_RPATH 160 bool "set rpath in the binary" if EXPERT 161 default y 162 depends on LD_SCRIPT_DYN 163 help 164 Add /lib (and /lib64 for 64-bit) to the linux binary's rpath 165 explicitly. 166 167 You may need to turn this off if compiling for nix systems 168 that have their libraries in random /nix directories and 169 might otherwise unexpected use libraries from /lib or /lib64 170 instead of the desired ones. 171 172config HOSTFS 173 tristate "Host filesystem" 174 help 175 While the User-Mode Linux port uses its own root file system for 176 booting and normal file access, this module lets the UML user 177 access files stored on the host. It does not require any 178 network connection between the Host and UML. An example use of 179 this might be: 180 181 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare 182 183 where /tmp/fromhost is an empty directory inside UML and 184 /tmp/umlshare is a directory on the host with files the UML user 185 wishes to access. 186 187 For more information, see 188 <http://user-mode-linux.sourceforge.net/hostfs.html>. 189 190 If you'd like to be able to work with files stored on the host, 191 say Y or M here; otherwise say N. 192 193config MCONSOLE 194 bool "Management console" 195 depends on PROC_FS 196 default y 197 help 198 The user mode linux management console is a low-level interface to 199 the kernel, somewhat like the i386 SysRq interface. Since there is 200 a full-blown operating system running under every user mode linux 201 instance, there is much greater flexibility possible than with the 202 SysRq mechanism. 203 204 If you answer 'Y' to this option, to use this feature, you need the 205 mconsole client (called uml_mconsole) which is present in CVS in 206 2.4.5-9um and later (path /tools/mconsole), and is also in the 207 distribution RPM package in 2.4.6 and later. 208 209 It is safe to say 'Y' here. 210 211config MAGIC_SYSRQ 212 bool "Magic SysRq key" 213 depends on MCONSOLE 214 help 215 If you say Y here, you will have some control over the system even 216 if the system crashes for example during kernel debugging (e.g., you 217 will be able to flush the buffer cache to disk, reboot the system 218 immediately or dump some status information). A key for each of the 219 possible requests is provided. 220 221 This is the feature normally accomplished by pressing a key 222 while holding SysRq (Alt+PrintScreen). 223 224 On UML, this is accomplished by sending a "sysrq" command with 225 mconsole, followed by the letter for the requested command. 226 227 The keys are documented in <file:Documentation/admin-guide/sysrq.rst>. Don't say Y 228 unless you really know what this hack does. 229 230config KERNEL_STACK_ORDER 231 int "Kernel stack size order" 232 default 2 if 64BIT 233 range 2 10 if 64BIT 234 default 1 if !64BIT 235 help 236 This option determines the size of UML kernel stacks. They will 237 be 1 << order pages. The default is OK unless you're running Valgrind 238 on UML, in which case, set this to 3. 239 It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on 240 older (pre-2017) CPUs. It is not recommended on newer CPUs due to the 241 increase in the size of the state which needs to be saved when handling 242 signals. 243 244config PGTABLE_LEVELS 245 int 246 default 4 if 64BIT 247 default 2 if !64BIT 248 249config UML_TIME_TRAVEL_SUPPORT 250 bool 251 prompt "Support time-travel mode (e.g. for test execution)" 252 # inf-cpu mode is incompatible with the benchmarking 253 depends on !RAID6_PQ_BENCHMARK 254 depends on !SMP 255 help 256 Enable this option to support time travel inside the UML instance. 257 258 After enabling this option, two modes are accessible at runtime 259 (selected by the kernel command line), see the kernel's command- 260 line help for more details. 261 262 It is safe to say Y, but you probably don't need this. 263 264config UML_MAX_USERSPACE_ITERATIONS 265 int 266 prompt "Maximum number of unscheduled userspace iterations" 267 default 10000 268 depends on UML_TIME_TRAVEL_SUPPORT 269 help 270 In UML inf-cpu and ext time-travel mode userspace can run without being 271 interrupted. This will eventually overwhelm the kernel and create OOM 272 situations (mainly RCU not running). This setting specifies the number 273 of kernel/userspace switches (minor/major page fault, signal or syscall) 274 for the same userspace thread before the sched_clock is advanced by a 275 jiffie to trigger scheduling. 276 277 Setting it to zero disables the feature. 278 279config KASAN_SHADOW_OFFSET 280 hex 281 depends on KASAN 282 default 0x100000000000 283 help 284 This is the offset at which the ~16TB of shadow memory is 285 mapped and used by KASAN for memory debugging. This can be any 286 address that has at least KASAN_SHADOW_SIZE (total address space divided 287 by 8) amount of space so that the KASAN shadow memory does not conflict 288 with anything. The default is 0x100000000000, which works even if mem is 289 set to a large value. On low-memory systems, try 0x7fff8000, as it fits 290 into the immediate of most instructions, improving performance. 291 292endmenu 293 294source "arch/um/drivers/Kconfig" 295 296config ARCH_SUSPEND_POSSIBLE 297 def_bool y 298 depends on !SMP 299 300menu "Power management options" 301 302source "kernel/power/Kconfig" 303 304endmenu 305