Re: [Qemu-devel] handling emulation fine-grained memory protection

[Richard Henderson]

On 07/03/2017 09:40 AM, Peter Maydell wrote:
> > Since these are defined by system registers, I can imagine there can only be
> > a few pages for which this fine grained handling might apply any any one
> > time. This would certainly be preferable to reducing the effectiveness of
> > the entire TLB by a factor of 16.
>
> Yes, that was somewhat my feeling too -- really tiny TLB pages
> are not very nice, and most pages probably won't be finegrained.

Coming back to this, might it make sense to choose a *larger* page size for M 
profile?  1K is awfully small.  Any idea how aligned the region start/end tends 
to be for real applications?

If we're only taking this extra trap for the first and last page of a region, 
when the application happens to use a size/alignment that conflicts with the 
page size that we choose, then a much larger page size choice might perform 
well overall.


r~