d911202e3f
I think that it's better to detect DMA misuse at build time rather than calling BUG_ON. Architectures that can't do DMA need to define CONFIG_NO_DMA. Thanks to Sam Ravnborg for explaining how CONFIG_NO_DMA and CONFIG_HAS_DMA work: http://marc.info/?l=linux-kernel&m=128359913825550&w=2 HAS_DMA is defined like this: config HAS_DMA boolean depends on !NO_DMA default y So to set HAS_DMA to true an arch should do: 1) Do not define NO_DMA 2) Define NO_DMA abd set it to 'n' Must archs - including um - used principle 1). In the um case we want to say that we do NOT have any DMA. This can be done in two ways. a) define NO_DMA and set it to 'y' b) redefine HAS_DMA and set it to 'n'. The patch you provided used principle b) where other archs use principle a). So I suggest you should use principle a) for um too. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Jeff Dike <jdike@addtoit.com> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
153 lines
5.1 KiB
Plaintext
153 lines
5.1 KiB
Plaintext
config STATIC_LINK
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bool "Force a static link"
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default n
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help
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This option gives you the ability to force a static link of UML.
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Normally, UML is linked as a shared binary. This is inconvenient for
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use in a chroot jail. So, if you intend to run UML inside a chroot,
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you probably want to say Y here.
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Additionally, this option enables using higher memory spaces (up to
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2.75G) for UML.
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source "mm/Kconfig"
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source "kernel/time/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 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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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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depends on 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/old/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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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 SMP
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bool "Symmetric multi-processing support (EXPERIMENTAL)"
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default n
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depends on 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
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gives 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 HIGHMEM
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bool "Highmem support (EXPERIMENTAL)"
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depends on !64BIT && EXPERIMENTAL
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default n
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help
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This was used to allow UML to run with big amounts of memory.
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Currently it is unstable, so if unsure say N.
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To use big amounts of memory, it is recommended enable static
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linking (i.e. CONFIG_STATIC_LINK) - this should allow the
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guest to use up to 2.75G of memory.
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config KERNEL_STACK_ORDER
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int "Kernel stack size order"
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default 1 if 64BIT
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range 1 10 if 64BIT
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default 0 if !64BIT
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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 NO_DMA
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def_bool y
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