On Mon, 4 Dec 2006, Matthew Wilcox wrote:
>
> CONFIG_LBD and CONFIG_LSF are spread into asm/types.h for no particularly
> good reason. Centralising the definition in linux/types.h means that arch
> maintainers don't need to bother adding it, as well as fixing the problem
> with x86-64 users being asked to make a decision that has absolutely no
> effect. The H8/300 porters seem particularly confused since I'm not aware
> of any microcontrollers that need to support 2TB filesystems.
Applied, since this is a good cleanup regardless.
I'd still be open to switching things around further, and allow even
64-bit architectures to say that they only want 32-bit sector_t's and page
indexes (ie remove the "depends on !64BIT" and make the "unsigned long"
case actually be "u32" instead, so that it literally switches between
32-bit or 64-bit values _regardless_ or architecture).
I don't know how big a deal it is, but I could imagine that we could
actually save memory in a smaller "struct page", for example, on 64bit
architectures by just using a 4-byte index.
For now, the !64BIT makes sense simply because a 64-bit architecture
probably doesn't care, and might as well just use 64 bits anyway (ie you
tend to have tons of memory there anyway). And I suspect it doesn't
actually even help on 64-bits due to structure alignment etc issues, but
am too lazy to go check.
Just thought I'd mention the possibility, in other words.
Linus
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