lkml.org 
[lkml]   [2005]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [patch 02/02] Debug option to write-protect rodata: the write protect logic and config option
From
Date
> people objecting to that.
> >
> > (It's not clear cut: while the last bit of the kernel no longer is
> > covered by a 2Mb tlb, most intel cpus have very few of such tlbs in the
> > first place and this would free up one such tlb for other things (say
> > the stack data) or even the userspace database), so it's not all that
> > clear cut what the cost of this is)
>
> I'm dumb. But how is "the last bit of the kernel no longer is covered
> by a 2Mb tlb"? Could you explain a bit more?

in memory it'll look something like this

0 2 4 6
-- kernel text -- + -- kernel text -- + --- k. text-- rodata -- + --

normally the range from 0 to 6 is covered with 2Mb tlb's.
Now to make rodata read only, the hugetlb entry covering 4-6 Mb range
needs to be split into 4Kb entries, so that the rodata portion can have
different permissions than the rest of that range.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-11-11 10:49    [W:0.418 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site