Re: cache problem

[Rene B. <re...@we...>]

Roman Zippel wrote:

>
> You need to boot with nobats, otherwise kernel_set_cachemode doesn't
> work.


Will try it.

>
> Anyway, in the long run kernel_set_cachemode shouldn't be used, it's
> simply isn't portable. The only problem is there isn't any standard
> interface yet to do this properly.
> Something like this is needed:
> vaddr =3D __vmalloc(size, GFP_KERNEL, _PAGE_NO_CACHE | _PAGE_GUARDED);
> for every page
> paddr =3D va_to_phys(vaddr);
>
> va_to_phys exists currently only for ppc, but it's quite generic code.
> For testing you can try it with nobats and we can change it later, but
> you should already take care to only work with single pages, that makes
> the conversion later easier.

As far as I know the standard interface to get some uncached mem is=20
pci_alloc_consistent() as described in Documentation/DMA-mapping.txt.=20
This seems to working on APUS, but I`m not sure if the TLB`s are marked=20
as cache-inhibit.


Ciao, Ren=E8