Re: [PATCH] [30/30] x86_64: Add missing !X86_PAE dependincy to the 2G/2G split.

[ebiederm@xmission.com (Eric W. Biederman)]

Bill Irwin <bill.irwin@oracle.com> writes:

>
> Only 1GB-aligned kernel/user splits are now handled for PAE. The
> 2GB/2GB split attempts to avoid aliasing vmallocspace with the 1:1
> mapping for physical memory by using an actual split of 1.875/2.125
> to accommodate 128MB of vmallocspace out of what would otherwise
> be a full 2GB for userspace. That attempt disturbs the alignment
> required by PAE for 2GB/2GB splits, and furthermore does not provide
> a 2GB/2GB split as advertised.
>
> This patch resolves the issues here in two manners. The first is
> by providing a true 2GB/2GB split in addition to the 1.875/2.125
> split. The second is by renaming the 1.875/2.125 split to
> CONFIG_VMSPLIT_2G_OPT analogously to CONFIG_VMSPLIT_3G_OPT, which
> performs a similar manuever to avoid aliasing vmallocspace with
> the 1:1 mapping for physical memory around the 3GB boundary. With
> the 1.875/2.125 split properly-named, its config option is then
> tagged as depending on !HIGHMEM to express the PAE implementation's
> current inability to deal with such unaligned splits.
>
> This patch is essentially a combination of two patches, one written
> by Eric Biederman and the other by Eric Dumazet. If they could add
> their Signed-off-by: to this, I'd be much obliged.
>
> Signed-off-by: William Irwin <wli@holomorphy.com>
> Cc: Eric Dumazet <dada1@cosmosbay.com>
> Cc: Mark Lord <lkml@rtr.ca>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Andi Kleen <ak@suse.de>

Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

>
>
> Index: sched/arch/i386/Kconfig
> ===================================================================
> --- sched.orig/arch/i386/Kconfig	2007-05-01 04:35:47.065162310 -0700
> +++ sched/arch/i386/Kconfig	2007-05-01 04:36:50.100754504 -0700
> @@ -571,6 +571,9 @@
>  		bool "3G/1G user/kernel split (for full 1G low memory)"
>  	config VMSPLIT_2G
>  		bool "2G/2G user/kernel split"
> +	config VMSPLIT_2G_OPT
> +		depends on !HIGHMEM
> +		bool "2G/2G user/kernel split (for full 2G low memory)"
>  	config VMSPLIT_1G
>  		bool "1G/3G user/kernel split"
>  endchoice
> @@ -578,7 +581,8 @@
>  config PAGE_OFFSET
>  	hex
>  	default 0xB0000000 if VMSPLIT_3G_OPT
> -	default 0x78000000 if VMSPLIT_2G
> +	default 0x80000000 if VMSPLIT_2G
> +	default 0x78000000 if VMSPLIT_2G_OPT
>  	default 0x40000000 if VMSPLIT_1G
>  	default 0xC0000000
>  
-
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