>What I'd do is extend alloc_area_pmd, alloc_area_pte and so on to take an
>extra argument to be the page protection value. The normal vmalloc can pass
>this in as just PAGE_KERNEL, and your new vmalloc_uncached can use some
>appropriate variant.
I wanted to avoid changing the non-arch specific code, but I beleive this
is the best way to do. We could define a generic GPF_UNCACHED flag too,
so this would make it useable with kmalloc too. This will be useful for
other non-coherent archs (like PowerMac Nubus).
>>or can I just alloc the area and then make pages non-cachable using
>>pte_modify afterwards ? In this case I'm not sure how to walk the PTEs...
>
>You *could* do it this way, but I don't think it's such a good idea.
I don't think neither.
>>Also alloc_are_pte makes several calls to __get_free_page, so I beleive
>>there's no way to make sure they are physically contiguous, is there ?
>
>No. This is always the case with vmalloc.
Ok. So I'll implement GPF_UNCACHED, and vmalloc_unached will simply pass
this instead of GPF_KERNEL. This way, we can have both vmalloc_uncached
and kmalloc(xxx, GPF_UNCACHED).
I'll also add a #define for the cache line size in asm/io.h and a function:
pci_device_is_cache_coherent(struct pcidev *dev)
which will hard-return true on coherent archs.
Linus, are you ok with that ?
--
Perso. e-mail: <mailto:bh40@calva.net>
Work e-mail: <mailto:benh@mipsys.com>
BenH. Web : <http://calvaweb.calvacom.fr/bh40/>
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