Re: enforcing page color matches
Masao Uebayashi
Masao
On Wed, May 25, 2011 at 4:36 PM, Matt Thomas <ma...@3am-software.com> wrote:
> I modified the mips pmap to drop into ddb if there was an attempt to map a page with an incorrect page color (color(VA) != color(PA)). Then using UVMHIST I fixed each cause. I can now boot a kernel on my matt-nb5-mips64 branch into sysinst with no bad color matches. I'm sure I haven't found all the cases but it's a big step forward.
>
> The diffs are relatively minor and are at www.netbsd.org/~matt/uvm-color-diffs.txt for your viewing enjoyment.
>
> I'm using a MIPS 74K which needs strict page-coloring enforcement (4 colors for its Icache and 2 colors for its Dcache) so this is important to me. If this can be enforced, the code to deal with bad colors can be removed and that will greatly simplify the mips pmap code.
>
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Matt Thomas
On May 25, 2011, at 8:11 AM, Eduardo Horvath wrote:
> On Wed, 25 May 2011, Matt Thomas wrote:
>
>> I'm using a MIPS 74K which needs strict page-coloring enforcement (4 colors for its Icache and 2 colors for its Dcache) so this is important to me. If this can be enforced, the code to deal with bad colors can be removed and that will greatly simplify the mips pmap code.
>
> I don't think that you can get rid of the page coloring code. What
> happens if you have two processes that have the same file mmap()ed to
> different page colors? But reducing the need for it is good.
I think the mmap for one of those mappings should fail.