1# SPDX-License-Identifier: GPL-2.0 2 3menu "UML-specific options" 4 5config UML 6 bool 7 default y 8 select ARCH_WANTS_DYNAMIC_TASK_STRUCT 9 select ARCH_HAS_CPU_FINALIZE_INIT 10 select ARCH_HAS_FORTIFY_SOURCE 11 select ARCH_HAS_GCOV_PROFILE_ALL 12 select ARCH_HAS_KCOV 13 select ARCH_HAS_STRNCPY_FROM_USER 14 select ARCH_HAS_STRNLEN_USER 15 select ARCH_HAS_STRICT_KERNEL_RWX 16 select HAVE_ARCH_AUDITSYSCALL 17 select HAVE_ARCH_KASAN if X86_64 18 select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN 19 select HAVE_ARCH_SECCOMP_FILTER 20 select HAVE_ASM_MODVERSIONS 21 select HAVE_UID16 22 select HAVE_DEBUG_KMEMLEAK 23 select HAVE_DEBUG_BUGVERBOSE 24 select HAVE_PAGE_SIZE_4KB 25 select NO_DMA if !UML_DMA_EMULATION 26 select OF_EARLY_FLATTREE if OF 27 select GENERIC_IRQ_SHOW 28 select GENERIC_CPU_DEVICES 29 select HAVE_GCC_PLUGINS 30 select ARCH_SUPPORTS_LTO_CLANG 31 select ARCH_SUPPORTS_LTO_CLANG_THIN 32 select TRACE_IRQFLAGS_SUPPORT 33 select TTY # Needed for line.c 34 select HAVE_ARCH_VMAP_STACK 35 select HAVE_RUST 36 select ARCH_HAS_UBSAN 37 select HAVE_ARCH_TRACEHOOK 38 select THREAD_INFO_IN_TASK 39 40config MMU 41 bool 42 default y 43 44config UML_DMA_EMULATION 45 bool 46 47config NO_IOMEM 48 bool "disable IOMEM" if EXPERT 49 depends on !INDIRECT_IOMEM 50 default y 51 52config UML_IOMEM_EMULATION 53 bool 54 select INDIRECT_IOMEM 55 select GENERIC_PCI_IOMAP 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 !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 4 if 64BIT 211 default 2 if !64BIT 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 UML_MAX_USERSPACE_ITERATIONS 229 int 230 prompt "Maximum number of unscheduled userspace iterations" 231 default 10000 232 depends on UML_TIME_TRAVEL_SUPPORT 233 help 234 In UML inf-cpu and ext time-travel mode userspace can run without being 235 interrupted. This will eventually overwhelm the kernel and create OOM 236 situations (mainly RCU not running). This setting specifies the number 237 of kernel/userspace switches (minor/major page fault, signal or syscall) 238 for the same userspace thread before the sched_clock is advanced by a 239 jiffie to trigger scheduling. 240 241 Setting it to zero disables the feature. 242 243config KASAN_SHADOW_OFFSET 244 hex 245 depends on KASAN 246 default 0x100000000000 247 help 248 This is the offset at which the ~16TB of shadow memory is 249 mapped and used by KASAN for memory debugging. This can be any 250 address that has at least KASAN_SHADOW_SIZE (total address space divided 251 by 8) amount of space so that the KASAN shadow memory does not conflict 252 with anything. The default is 0x100000000000, which works even if mem is 253 set to a large value. On low-memory systems, try 0x7fff8000, as it fits 254 into the immediate of most instructions, improving performance. 255 256endmenu 257 258source "arch/um/drivers/Kconfig" 259 260config ARCH_SUSPEND_POSSIBLE 261 def_bool y 262 263menu "Power management options" 264 265source "kernel/power/Kconfig" 266 267endmenu 268