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