# UML uses the generic IRQ sugsystem config GENERIC_HARDIRQS bool default y config UML bool default y # XXX: does UM have a mmu/swap? config MMU bool default y mainmenu "Linux/Usermode Kernel Configuration" config ISA bool config SBUS bool config PCI bool config UID16 bool default y config RWSEM_GENERIC_SPINLOCK bool default y config GENERIC_CALIBRATE_DELAY bool default y # Used in kernel/irq/manage.c and include/linux/irq.h config IRQ_RELEASE_METHOD bool default y menu "UML-specific options" config MODE_TT bool "Tracing thread support" default y help This option controls whether tracing thread support is compiled into UML. Normally, this should be set to Y. If you intend to use only skas mode (and the host has the skas patch applied to it), then it is OK to say N here. config STATIC_LINK bool "Force a static link" default n depends on !MODE_TT help If CONFIG_MODE_TT is disabled, then this option gives you the ability to force a static link of UML. Normally, if only skas mode is built in to UML, it will be linked as a shared binary. This is inconvenient for use in a chroot jail. So, if you intend to run UML inside a chroot, and you disable CONFIG_MODE_TT, you probably want to say Y here. config MODE_SKAS bool "Separate Kernel Address Space support" default y help This option controls whether skas (separate kernel address space) support is compiled in. If you have applied the skas patch to the host, then you certainly want to say Y here (and consider saying N to CONFIG_MODE_TT). Otherwise, it is safe to say Y. Disabling this option will shrink the UML binary slightly. source "arch/um/Kconfig_arch" source "mm/Kconfig" config LD_SCRIPT_STATIC bool default y depends on MODE_TT || STATIC_LINK config LD_SCRIPT_DYN bool default y depends on !LD_SCRIPT_STATIC config NET bool "Networking support" help Unless you really know what you are doing, you should say Y here. The reason is that some programs need kernel networking support even when running on a stand-alone machine that isn't connected to any other computer. If you are upgrading from an older kernel, you should consider updating your networking tools too because changes in the kernel and the tools often go hand in hand. The tools are contained in the package net-tools, the location and version number of which are given in . For a general introduction to Linux networking, it is highly recommended to read the NET-HOWTO, available from . source "fs/Kconfig.binfmt" config HOSTFS tristate "Host filesystem" help While the User-Mode Linux port uses its own root file system for booting and normal file access, this module lets the UML user access files stored on the host. It does not require any network connection between the Host and UML. An example use of this might be: mount none /tmp/fromhost -t hostfs -o /tmp/umlshare where /tmp/fromhost is an empty directory inside UML and /tmp/umlshare is a directory on the host with files the UML user wishes to access. For more information, see . If you'd like to be able to work with files stored on the host, say Y or M here; otherwise say N. config HPPFS tristate "HoneyPot ProcFS (EXPERIMENTAL)" help hppfs (HoneyPot ProcFS) is a filesystem which allows UML /proc entries to be overridden, removed, or fabricated from the host. Its purpose is to allow a UML to appear to be a physical machine by removing or changing anything in /proc which gives away the identity of a UML. See for more information. You only need this if you are setting up a UML honeypot. Otherwise, it is safe to say 'N' here. If you are actively using it, please report any problems, since it's getting fixed. In this moment, it is experimental on 2.6 (it works on 2.4). config MCONSOLE bool "Management console" default y help The user mode linux management console is a low-level interface to the kernel, somewhat like the i386 SysRq interface. Since there is a full-blown operating system running under every user mode linux instance, there is much greater flexibility possible than with the SysRq mechanism. If you answer 'Y' to this option, to use this feature, you need the mconsole client (called uml_mconsole) which is present in CVS in 2.4.5-9um and later (path /tools/mconsole), and is also in the distribution RPM package in 2.4.6 and later. It is safe to say 'Y' here. config MAGIC_SYSRQ bool "Magic SysRq key" depends on MCONSOLE ---help--- If you say Y here, you will have some control over the system even if the system crashes for example during kernel debugging (e.g., you will be able to flush the buffer cache to disk, reboot the system immediately or dump some status information). A key for each of the possible requests is provided. This is the feature normally accomplished by pressing a key while holding SysRq (Alt+PrintScreen). On UML, this is accomplished by sending a "sysrq" command with mconsole, followed by the letter for the requested command. The keys are documented in . Don't say Y unless you really know what this hack does. config HOST_2G_2G bool "2G/2G host address space split" default n help This is needed when the host on which you run has a 2G/2G memory split, instead of the customary 3G/1G. Note that to enable such a host configuration, which makes sense only in some cases, you need special host patches. So, if you do not know what to do here, say 'N'. config SMP bool "Symmetric multi-processing support (EXPERIMENTAL)" default n depends on MODE_TT && EXPERIMENTAL help This option enables UML SMP support. It is NOT related to having a real SMP box. Not directly, at least. UML implements virtual SMP by allowing as many processes to run simultaneously on the host as there are virtual processors configured. Obviously, if the host is a uniprocessor, those processes will timeshare, but, inside UML, will appear to be running simultaneously. If the host is a multiprocessor, then UML processes may run simultaneously, depending on the host scheduler. This, however, is supported only in TT mode. So, if you use the SKAS patch on your host, switching to TT mode and enabling SMP usually gives you worse performances. Also, since the support for SMP has been under-developed, there could be some bugs being exposed by enabling SMP. If you don't know what to do, say N. config NR_CPUS int "Maximum number of CPUs (2-32)" range 2 32 depends on SMP default "32" config NEST_LEVEL int "Nesting level" default "0" help This is set to the number of layers of UMLs that this UML will be run in. Normally, this is zero, meaning that it will run directly on the host. Setting it to one will build a UML that can run inside a UML that is running on the host. Generally, if you intend this UML to run inside another UML, set CONFIG_NEST_LEVEL to one more than the host UML. Note that if the hosting UML has its CONFIG_KERNEL_HALF_GIGS set to greater than one, then the guest UML should have its CONFIG_NEST_LEVEL set to the host's CONFIG_NEST_LEVEL + CONFIG_KERNEL_HALF_GIGS. Only change this if you are running nested UMLs. config KERNEL_HALF_GIGS int "Kernel address space size (in .5G units)" default "1" help This determines the amount of address space that UML will allocate for its own, measured in half Gigabyte units. The default is 1. Change this only if you need to boot UML with an unusually large amount of physical memory. config HIGHMEM bool "Highmem support" depends on !64BIT config KERNEL_STACK_ORDER int "Kernel stack size order" default 2 help This option determines the size of UML kernel stacks. They will be 1 << order pages. The default is OK unless you're running Valgrind on UML, in which case, set this to 3. config UML_REAL_TIME_CLOCK bool "Real-time Clock" default y help This option makes UML time deltas match wall clock deltas. This should normally be enabled. The exception would be if you are debugging with UML and spend long times with UML stopped at a breakpoint. In this case, when UML is restarted, it will call the timer enough times to make up for the time spent at the breakpoint. This could result in a noticable lag. If this is a problem, then disable this option. endmenu source "init/Kconfig" source "net/Kconfig" source "drivers/base/Kconfig" source "arch/um/Kconfig_char" source "drivers/block/Kconfig" config NETDEVICES bool default NET source "arch/um/Kconfig_net" source "drivers/net/Kconfig" source "fs/Kconfig" source "security/Kconfig" source "crypto/Kconfig" source "lib/Kconfig" menu "SCSI support" depends on BROKEN config SCSI tristate "SCSI support" # This gives us free_dma, which scsi.c wants. config GENERIC_ISA_DMA bool depends on SCSI default y source "arch/um/Kconfig_scsi" endmenu source "drivers/md/Kconfig" if BROKEN source "drivers/mtd/Kconfig" endif #This is just to shut up some Kconfig warnings, so no prompt. config INPUT bool default n source "arch/um/Kconfig.debug"