c21be1c9c1
Now that various memory splits are enabled, add a config option allowing the user to compile UML for its need - HOST_2G_2G allowed to choose either 3G/1G or 2G/2G, and enabling it reduced the usable virtual memory. Detecting this at run time should be implemented in the future, but we must make the stop-gap measure work well enough (this is valid in _many_ cases). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
94 lines
2.2 KiB
Plaintext
94 lines
2.2 KiB
Plaintext
menu "Host processor type and features"
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source "arch/i386/Kconfig.cpu"
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endmenu
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config UML_X86
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bool
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default y
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config 64BIT
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bool
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default n
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config SEMAPHORE_SLEEPERS
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bool
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default y
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choice
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prompt "Host memory split"
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default HOST_VMSPLIT_3G
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---help---
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This is needed when the host kernel on which you run has a non-default
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(like 2G/2G) memory split, instead of the customary 3G/1G. If you did
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not recompile your own kernel but use the default distro's one, you can
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safely accept the "Default split" option.
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It can be enabled on recent (>=2.6.16-rc2) vanilla kernels via
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CONFIG_VM_SPLIT_*, or on previous kernels with special patches (-ck
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patchset by Con Kolivas, or other ones) - option names match closely the
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host CONFIG_VM_SPLIT_* ones.
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A lower setting (where 1G/3G is lowest and 3G/1G is higher) will
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tolerate even more "normal" host kernels, but an higher setting will be
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stricter.
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So, if you do not know what to do here, say 'Default split'.
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config HOST_VMSPLIT_3G
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bool "Default split (3G/1G user/kernel host split)"
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config HOST_VMSPLIT_3G_OPT
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bool "3G/1G user/kernel host split (for full 1G low memory)"
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config HOST_VMSPLIT_2G
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bool "2G/2G user/kernel host split"
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config HOST_VMSPLIT_1G
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bool "1G/3G user/kernel host split"
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endchoice
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config TOP_ADDR
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hex
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default 0xB0000000 if HOST_VMSPLIT_3G_OPT
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default 0x78000000 if HOST_VMSPLIT_2G
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default 0x40000000 if HOST_VMSPLIT_1G
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default 0xC0000000
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config 3_LEVEL_PGTABLES
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bool "Three-level pagetables (EXPERIMENTAL)"
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default n
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depends on EXPERIMENTAL
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help
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Three-level pagetables will let UML have more than 4G of physical
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memory. All the memory that can't be mapped directly will be treated
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as high memory.
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However, this it experimental on 32-bit architectures, so if unsure say
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N (on x86-64 it's automatically enabled, instead, as it's safe there).
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config STUB_CODE
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hex
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default 0xbfffe000 if !HOST_2G_2G
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default 0x7fffe000 if HOST_2G_2G
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config STUB_DATA
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hex
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default 0xbffff000 if !HOST_2G_2G
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default 0x7ffff000 if HOST_2G_2G
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config STUB_START
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hex
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default STUB_CODE
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config ARCH_HAS_SC_SIGNALS
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bool
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default y
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config ARCH_REUSE_HOST_VSYSCALL_AREA
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bool
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default y
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config GENERIC_HWEIGHT
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bool
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default y
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