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Commit c21be1c9 authored by Paolo 'Blaisorblade' Giarrusso's avatar Paolo 'Blaisorblade' Giarrusso Committed by Linus Torvalds
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[PATCH] uml: allow finer tuning for host VMSPLIT setting 



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: default avatarPaolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ca316fcf

arch/um/Kconfig.i386

+34 −15
Original line number Diff line number Diff line
@@ -16,23 +16,42 @@ config SEMAPHORE_SLEEPERS 
	bool

	default y



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'.

choice

	prompt "Host memory split"

	default HOST_VMSPLIT_3G

	---help---

	   This is needed when the host kernel on which you run has a non-default

	   (like 2G/2G) memory split, instead of the customary 3G/1G. If you did

	   not recompile your own kernel but use the default distro's one, you can

	   safely accept the "Default split" option.



	   It can be enabled on recent (>=2.6.16-rc2) vanilla kernels via

	   CONFIG_VM_SPLIT_*, or on previous kernels with special patches (-ck

	   patchset by Con Kolivas, or other ones) - option names match closely the

	   host CONFIG_VM_SPLIT_* ones.



	   A lower setting (where 1G/3G is lowest and 3G/1G is higher) will

	   tolerate even more "normal" host kernels, but an higher setting will be

	   stricter.



	   So, if you do not know what to do here, say 'Default split'.



	config HOST_VMSPLIT_3G

		bool "Default split (3G/1G user/kernel host split)"

	config HOST_VMSPLIT_3G_OPT

		bool "3G/1G user/kernel host split (for full 1G low memory)"

	config HOST_VMSPLIT_2G

		bool "2G/2G user/kernel host split"

	config HOST_VMSPLIT_1G

		bool "1G/3G user/kernel host split"

endchoice



config TOP_ADDR

	hex

 	default 0xc0000000 if !HOST_2G_2G

 	default 0x80000000 if HOST_2G_2G

	default 0xB0000000 if HOST_VMSPLIT_3G_OPT

	default 0x78000000 if HOST_VMSPLIT_2G

	default 0x40000000 if HOST_VMSPLIT_1G

	default 0xC0000000



config 3_LEVEL_PGTABLES

	bool "Three-level pagetables (EXPERIMENTAL)"