![Jeff Dike](/assets/img/avatar_default.png)
Noticed by Al Viro <viro@parcelfarce.linux.theplanet.co.uk> - SMP on x86_64 is fundamentally broken due to UML's reuse of the host arch's percpu stuff. This is OK on x86, but the x86_64 pda stuff just won't work for UML. Signed-off-by: Jeff Dike <jdike@addtoit.com> Cc: Paolo Giarrusso <blaisorblade@yahoo.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
330 lines
9.3 KiB
Text
330 lines
9.3 KiB
Text
# UML uses the generic IRQ sugsystem
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config GENERIC_HARDIRQS
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bool
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default y
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config UML
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bool
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default y
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# XXX: does UM have a mmu/swap?
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config MMU
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bool
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default y
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mainmenu "Linux/Usermode Kernel Configuration"
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config ISA
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bool
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config SBUS
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bool
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config PCI
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bool
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config UID16
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bool
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default y
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config RWSEM_GENERIC_SPINLOCK
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bool
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default y
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config GENERIC_CALIBRATE_DELAY
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bool
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default y
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# Used in kernel/irq/manage.c and include/linux/irq.h
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config IRQ_RELEASE_METHOD
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bool
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default y
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menu "UML-specific options"
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config MODE_TT
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bool "Tracing thread support"
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default y
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help
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This option controls whether tracing thread support is compiled
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into UML. Normally, this should be set to Y. If you intend to
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use only skas mode (and the host has the skas patch applied to it),
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then it is OK to say N here.
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config STATIC_LINK
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bool "Force a static link"
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default n
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depends on !MODE_TT
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help
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If CONFIG_MODE_TT is disabled, then this option gives you the ability
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to force a static link of UML. Normally, if only skas mode is built
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in to UML, it will be linked as a shared binary. This is inconvenient
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for use in a chroot jail. So, if you intend to run UML inside a
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chroot, and you disable CONFIG_MODE_TT, you probably want to say Y
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here.
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config MODE_SKAS
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bool "Separate Kernel Address Space support"
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default y
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help
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This option controls whether skas (separate kernel address space)
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support is compiled in. If you have applied the skas patch to the
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host, then you certainly want to say Y here (and consider saying N
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to CONFIG_MODE_TT). Otherwise, it is safe to say Y. Disabling this
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option will shrink the UML binary slightly.
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source "arch/um/Kconfig.arch"
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source "mm/Kconfig"
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config LD_SCRIPT_STATIC
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bool
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default y
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depends on MODE_TT || STATIC_LINK
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config LD_SCRIPT_DYN
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bool
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default y
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depends on !LD_SCRIPT_STATIC
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config NET
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bool "Networking support"
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help
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Unless you really know what you are doing, you should say Y here.
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The reason is that some programs need kernel networking support even
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when running on a stand-alone machine that isn't connected to any
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other computer. If you are upgrading from an older kernel, you
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should consider updating your networking tools too because changes
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in the kernel and the tools often go hand in hand. The tools are
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contained in the package net-tools, the location and version number
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of which are given in <file:Documentation/Changes>.
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For a general introduction to Linux networking, it is highly
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recommended to read the NET-HOWTO, available from
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<http://www.tldp.org/docs.html#howto>.
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source "fs/Kconfig.binfmt"
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config HOSTFS
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tristate "Host filesystem"
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help
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While the User-Mode Linux port uses its own root file system for
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booting and normal file access, this module lets the UML user
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access files stored on the host. It does not require any
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network connection between the Host and UML. An example use of
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this might be:
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mount none /tmp/fromhost -t hostfs -o /tmp/umlshare
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where /tmp/fromhost is an empty directory inside UML and
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/tmp/umlshare is a directory on the host with files the UML user
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wishes to access.
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For more information, see
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<http://user-mode-linux.sourceforge.net/hostfs.html>.
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If you'd like to be able to work with files stored on the host,
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say Y or M here; otherwise say N.
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config HPPFS
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tristate "HoneyPot ProcFS (EXPERIMENTAL)"
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help
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hppfs (HoneyPot ProcFS) is a filesystem which allows UML /proc
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entries to be overridden, removed, or fabricated from the host.
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Its purpose is to allow a UML to appear to be a physical machine
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by removing or changing anything in /proc which gives away the
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identity of a UML.
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See <http://user-mode-linux.sf.net/hppfs.html> for more information.
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You only need this if you are setting up a UML honeypot. Otherwise,
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it is safe to say 'N' here.
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If you are actively using it, please report any problems, since it's
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getting fixed. In this moment, it is experimental on 2.6 (it works on
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2.4).
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config MCONSOLE
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bool "Management console"
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default y
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help
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The user mode linux management console is a low-level interface to
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the kernel, somewhat like the i386 SysRq interface. Since there is
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a full-blown operating system running under every user mode linux
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instance, there is much greater flexibility possible than with the
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SysRq mechanism.
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If you answer 'Y' to this option, to use this feature, you need the
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mconsole client (called uml_mconsole) which is present in CVS in
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2.4.5-9um and later (path /tools/mconsole), and is also in the
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distribution RPM package in 2.4.6 and later.
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It is safe to say 'Y' here.
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config MAGIC_SYSRQ
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bool "Magic SysRq key"
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depends on MCONSOLE
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---help---
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If you say Y here, you will have some control over the system even
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if the system crashes for example during kernel debugging (e.g., you
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will be able to flush the buffer cache to disk, reboot the system
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immediately or dump some status information). A key for each of the
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possible requests is provided.
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This is the feature normally accomplished by pressing a key
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while holding SysRq (Alt+PrintScreen).
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On UML, this is accomplished by sending a "sysrq" command with
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mconsole, followed by the letter for the requested command.
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The keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
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unless you really know what this hack does.
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config HOST_2G_2G
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bool "2G/2G host address space split"
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default n
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help
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This is needed when the host on which you run has a 2G/2G memory
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split, instead of the customary 3G/1G.
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Note that to enable such a host
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configuration, which makes sense only in some cases, you need special
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host patches.
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So, if you do not know what to do here, say 'N'.
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config SMP
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bool "Symmetric multi-processing support (EXPERIMENTAL)"
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default n
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depends on (MODE_TT && EXPERIMENTAL && !SMP_BROKEN) || (BROKEN && SMP_BROKEN)
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help
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This option enables UML SMP support.
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It is NOT related to having a real SMP box. Not directly, at least.
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UML implements virtual SMP by allowing as many processes to run
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simultaneously on the host as there are virtual processors configured.
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Obviously, if the host is a uniprocessor, those processes will
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timeshare, but, inside UML, will appear to be running simultaneously.
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If the host is a multiprocessor, then UML processes may run
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simultaneously, depending on the host scheduler.
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This, however, is supported only in TT mode. So, if you use the SKAS
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patch on your host, switching to TT mode and enabling SMP usually gives
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you worse performances.
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Also, since the support for SMP has been under-developed, there could
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be some bugs being exposed by enabling SMP.
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If you don't know what to do, say N.
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config NR_CPUS
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int "Maximum number of CPUs (2-32)"
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range 2 32
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depends on SMP
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default "32"
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config NEST_LEVEL
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int "Nesting level"
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default "0"
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help
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This is set to the number of layers of UMLs that this UML will be run
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in. Normally, this is zero, meaning that it will run directly on the
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host. Setting it to one will build a UML that can run inside a UML
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that is running on the host. Generally, if you intend this UML to run
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inside another UML, set CONFIG_NEST_LEVEL to one more than the host
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UML.
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Note that if the hosting UML has its CONFIG_KERNEL_HALF_GIGS set to
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greater than one, then the guest UML should have its CONFIG_NEST_LEVEL
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set to the host's CONFIG_NEST_LEVEL + CONFIG_KERNEL_HALF_GIGS.
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Only change this if you are running nested UMLs.
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config KERNEL_HALF_GIGS
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int "Kernel address space size (in .5G units)"
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default "1"
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help
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This determines the amount of address space that UML will allocate for
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its own, measured in half Gigabyte units. The default is 1.
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Change this only if you need to boot UML with an unusually large amount
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of physical memory.
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config HIGHMEM
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bool "Highmem support"
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depends on !64BIT
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config KERNEL_STACK_ORDER
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int "Kernel stack size order"
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default 2
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help
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This option determines the size of UML kernel stacks. They will
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be 1 << order pages. The default is OK unless you're running Valgrind
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on UML, in which case, set this to 3.
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config UML_REAL_TIME_CLOCK
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bool "Real-time Clock"
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default y
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help
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This option makes UML time deltas match wall clock deltas. This should
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normally be enabled. The exception would be if you are debugging with
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UML and spend long times with UML stopped at a breakpoint. In this
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case, when UML is restarted, it will call the timer enough times to make
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up for the time spent at the breakpoint. This could result in a
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noticable lag. If this is a problem, then disable this option.
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endmenu
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source "init/Kconfig"
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source "net/Kconfig"
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source "drivers/base/Kconfig"
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source "arch/um/Kconfig.char"
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source "drivers/block/Kconfig"
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config NETDEVICES
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bool
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default NET
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source "arch/um/Kconfig.net"
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source "drivers/net/Kconfig"
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source "fs/Kconfig"
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source "security/Kconfig"
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source "crypto/Kconfig"
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source "lib/Kconfig"
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menu "SCSI support"
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depends on BROKEN
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config SCSI
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tristate "SCSI support"
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# This gives us free_dma, which scsi.c wants.
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config GENERIC_ISA_DMA
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bool
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depends on SCSI
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default y
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source "arch/um/Kconfig.scsi"
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endmenu
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source "drivers/md/Kconfig"
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if BROKEN
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source "drivers/mtd/Kconfig"
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endif
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#This is just to shut up some Kconfig warnings, so no prompt.
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config INPUT
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bool
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default n
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source "arch/um/Kconfig.debug"
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