On Tue, 10 Jan 2006, Jens Axboe wrote:

Can we do one final cleanup? Do all the magic in _one_ place, namely the x86 Kconfig file.

Also, I don't think the NOHIGHMEM dependency is necessarily correct. A 2G/2G split can be advantageous with a 16GB setup (you'll have more room for dentries etc), but you obviously want to have HIGHMEM for that..

Do it something like this:

choice depends on EXPERIMENTAL prompt "Memory split" default DEFAULT_3G help Select the wanted split between kernel and user memory. If the address range available to the kernel is less than the physical memory installed, the remaining memory will be available as "high memory". Accessing high memory is a little more costly than low memory, as it needs to be mapped into the kernel first. Note that selecting anything but the default 3G/1G split will make your kernel incompatible with binary only modules.

config DEFAULT_3G bool "3G/1G user/kernel split" config DEFAULT_3G_OPT bool "3G/1G user/kernel split (for full 1G low memory)" config DEFAULT_2G bool "2G/2G user/kernel split" config DEFAULT_1G bool "1G/3G user/kernel split" endchoice

config PAGE_OFFSET hex default 0xC0000000 default 0xB0000000 if DEFAULT_3G_OPT default 0x78000000 if DEFAULT_2G default 0x40000000 if DEFAULT_1G

and then asm-i386/page.h can just do

#define __PAGE_OFFSET ((unsigned long)CONFIG_PAGE_OFFSET)

and you're done.

If you ever want to change the offsets, you're only changing the Kconfig file, and as you can tell, the syntax is actually much _nicer_ that using the C preprocessor, since these kinds of choices is exactly what the Kconfig language is all about.

Please?

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