Re: cache problem

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

Ken Tyler wrote:

>
> Hello,
>
> Don't understand what you mean by "last page" or "upper boundary of siz=
e".
>
> Do you mean if I :
>
> page =3D __get_free_pages(GFP_ATOMIC,1);
>
> which allocates two pages, the second of which does not have cache mode
> set correctly ?


Hi,

OK, I`l describe it. If you use __get_free_pages(GFP_ATOMIC, 1) you get=20
2 pages and you will probably apply 8192 to the size argument of=20
kernel_set_cachemode(). Thats OK.
But if you apply sizeof(struct x) to the size argument and sizeof(struct=20
x) isn`t a multiply of PAGE_SIZE then the last page is not remapped by=20
kernel_set_cachemode(). Because the loop in kernel_set_cachemode() is=20
initialized at value: size =3D size / PAGE_SIZE.
If size =3D 10000, so you have to remap 3 pages, but 10000 / 4096 =3D=20
2(u_long) and the loop only remaps 2 pages.

I hope now its clear what I mean.

>
> Thinking about yet another play with the A4091...


It`s weekend, have fun...


Ciao, Ren=E8