5 # XXX: does UM have a mmu/swap?
10 mainmenu "Linux/Usermode Kernel Configuration"
25 config RWSEM_GENERIC_SPINLOCK
29 menu "UML-specific options"
32 bool "Tracing thread support"
35 This option controls whether tracing thread support is compiled
36 into UML. Normally, this should be set to Y. If you intend to
37 use only skas mode (and the host has the skas patch applied to it),
38 then it is OK to say N here.
41 bool "Force a static link"
45 If CONFIG_MODE_TT is disabled, then this option gives you the ability
46 to force a static link of UML. Normally, if only skas mode is built
47 in to UML, it will be linked as a shared binary. This is inconvenient
48 for use in a chroot jail. So, if you intend to run UML inside a
49 chroot, and you disable CONFIG_MODE_TT, you probably want to say Y
53 bool "Separate Kernel Address Space support"
56 This option controls whether skas (separate kernel address space)
57 support is compiled in. If you have applied the skas patch to the
58 host, then you certainly want to say Y here (and consider saying N
59 to CONFIG_MODE_TT). Otherwise, it is safe to say Y. Disabling this
60 option will shrink the UML binary slightly.
63 bool "Networking support"
65 Unless you really know what you are doing, you should say Y here.
66 The reason is that some programs need kernel networking support even
67 when running on a stand-alone machine that isn't connected to any
68 other computer. If you are upgrading from an older kernel, you
69 should consider updating your networking tools too because changes
70 in the kernel and the tools often go hand in hand. The tools are
71 contained in the package net-tools, the location and version number
72 of which are given in Documentation/Changes.
74 For a general introduction to Linux networking, it is highly
75 recommended to read the NET-HOWTO, available from
76 <http://www.tldp.org/docs.html#howto>.
79 source "fs/Kconfig.binfmt"
82 tristate "Support for host-based filesystems"
85 tristate "Host filesystem"
87 While the User-Mode Linux port uses its own root file system for
88 booting and normal file access, this module lets the UML user
89 access files stored on the host. It does not require any
90 network connection between the Host and UML. An example use of
93 mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
95 where /tmp/fromhost is an empty directory inside UML and
96 /tmp/umlshare is a directory on the host with files the UML user
99 For more information, see
100 <http://user-mode-linux.sourceforge.net/hostfs.html>.
102 If you'd like to be able to work with files stored on the host,
103 say Y or M here; otherwise say N.
106 tristate 'Usable host filesystem'
110 tristate "HoneyPot ProcFS"
112 hppfs (HoneyPot ProcFS) is a filesystem which allows UML /proc
113 entries to be overridden, removed, or fabricated from the host.
114 Its purpose is to allow a UML to appear to be a physical machine
115 by removing or changing anything in /proc which gives away the
118 See http://user-mode-linux.sf.net/hppfs.html for more information.
120 You only need this if you are setting up a UML honeypot. Otherwise,
121 it is safe to say 'N' here.
124 bool "Management console"
126 The user mode linux management console is a low-level interface to
127 the kernel, somewhat like the i386 SysRq interface. Since there is
128 a full-blown operating system running under every user mode linux
129 instance, there is much greater flexibility possible than with the
132 If you answer 'Y' to this option, to use this feature, you need the
133 mconsole client (called uml_mconsole) which is present in CVS in
134 2.4.5-9um and later (path /tools/mconsole), and is also in the
135 distribution RPM package in 2.4.6 and later.
137 It is safe to say 'Y' here.
140 bool "Magic SysRq key"
143 If you say Y here, you will have some control over the system even
144 if the system crashes for example during kernel debugging (e.g., you
145 will be able to flush the buffer cache to disk, reboot the system
146 immediately or dump some status information). This is accomplished
147 by pressing various keys while holding SysRq (Alt+PrintScreen). It
148 also works on a serial console (on PC hardware at least), if you
149 send a BREAK and then within 5 seconds a command keypress. The
150 keys are documented in Documentation/sysrq.txt. Don't say Y
151 unless you really know what this hack does.
154 bool "2G/2G host address space split"
157 bool "Symmetric multi-processing support"
159 This option enables UML SMP support. UML implements virtual SMP by
160 allowing as many processes to run simultaneously on the host as
161 there are virtual processors configured. Obviously, if the host is
162 a uniprocessor, those processes will timeshare, but, inside UML,
163 will appear to be running simultaneously. If the host is a
164 multiprocessor, then UML processes may run simultaneously, depending
165 on the host scheduler.
166 CONFIG_SMP will be set to whatever this option is set to.
167 It is safe to leave this unchanged.
174 int "Maximum number of CPUs (2-32)"
183 This is set to the number of layers of UMLs that this UML will be run
184 in. Normally, this is zero, meaning that it will run directly on the
185 host. Setting it to one will build a UML that can run inside a UML
186 that is running on the host. Generally, if you intend this UML to run
187 inside another UML, set CONFIG_NEST_LEVEL to one more than the host
190 Note that if the hosting UML has its CONFIG_KERNEL_HALF_GIGS set to
191 greater than one, then the guest UML should have its CONFIG_NEST_LEVEL
192 set to the host's CONFIG_NEST_LEVEL + CONFIG_KERNEL_HALF_GIGS.
193 Only change this if you are running nested UMLs.
195 config KERNEL_HALF_GIGS
196 int "Kernel address space size (in .5G units)"
199 This determines the amount of address space that UML will allocate for
200 its own, measured in half Gigabyte units. The default is 1.
201 Change this only if you need to boot UML with an unusually large amount
205 bool "Highmem support"
208 bool "/proc/mm support"
210 config KERNEL_STACK_ORDER
211 int "Kernel stack size order"
214 This option determines the size of UML kernel stacks. They will
215 be 1 << order pages. The default is OK unless you're running Valgrind
216 on UML, in which case, set this to 3.
218 config UML_REAL_TIME_CLOCK
219 bool "Real-time Clock"
222 This option makes UML time deltas match wall clock deltas. This should
223 normally be enabled. The exception would be if you are debugging with
224 UML and spend long times with UML stopped at a breakpoint. In this
225 case, when UML is restarted, it will call the timer enough times to make
226 up for the time spent at the breakpoint. This could result in a
227 noticable lag. If this is a problem, then disable this option.
231 source "init/Kconfig"
233 source "drivers/base/Kconfig"
235 source "arch/um/Kconfig_char"
237 source "arch/um/Kconfig_block"
243 source "arch/um/Kconfig_net"
249 source "kernel/vserver/Kconfig"
251 source "security/Kconfig"
253 source "crypto/Kconfig"
260 tristate "SCSI support"
262 # This gives us free_dma, which scsi.c wants.
263 config GENERIC_ISA_DMA
268 source "arch/um/Kconfig_scsi"
272 source "drivers/md/Kconfig"
274 source "drivers/mtd/Kconfig"
277 menu "Kernel hacking"
280 bool "Debug memory allocations"
282 config DEBUG_SPINLOCK
283 bool "Debug spinlocks usage"
286 bool "Enable kernel debugging symbols"
288 When this is enabled, the User-Mode Linux binary will include
289 debugging symbols. This enlarges the binary by a few megabytes,
290 but aids in tracking down kernel problems in UML. It is required
291 if you intend to do any kernel development.
293 If you're truly short on disk space or don't expect to report any
294 bugs back to the UML developers, say N, otherwise say Y.
298 default y if DEBUG_INFO
301 bool "Enable ptrace proxy"
302 depends on XTERM_CHAN && DEBUG_INFO
304 This option enables a debugging interface which allows gdb to debug
305 the kernel without needing to actually attach to kernel threads.
306 If you want to do kernel debugging, say Y here; otherwise say N.
309 bool "Enable gprof support"
310 depends on DEBUG_INFO
312 This allows profiling of a User-Mode Linux kernel with the gprof
315 See <http://user-mode-linux.sourceforge.net/gprof.html> for more
318 If you're involved in UML kernel development and want to use gprof,
319 say Y. If you're unsure, say N.
322 bool "Enable gcov support"
323 depends on DEBUG_INFO
325 This option allows developers to retrieve coverage data from a UML
328 See <http://user-mode-linux.sourceforge.net/gprof.html> for more
331 If you're involved in UML kernel development and want to use gcov,
332 say Y. If you're unsure, say N.