[PATCH, PPC] Use 64k for COMMONPAGESIZE
Thu Dec 18 07:06:00 GMT 2014
On 18/12/14 07:11, Alan Modra wrote:
> On Thu, Dec 18, 2014 at 10:26:03AM +1100, Chris Johns wrote:
>> >On 17/12/2014 12:34 pm, Richard Henderson wrote:
>>> > >It seems to me that most powerpc hardware these days is server based, and very
>>> > >little remains at the desktop class.
There are not only servers and desktops in the world. We have also
>> >What about embedded devices with as Freescale's QorIQ T2080 and T4240 ?
>>> > >And in the server environment, IBM has
>>> > >been recommending a 64k page size.
>> >Would this change effect RTEMS and it devices ?
> Yes, it would. However, the effect isn't huge one way or another.
> Richard quoting IBM's recommendation of a 64k page size really hasn't
> anything to do with COMMONPAGESIZE, or at least not as much as you
> might think.. You can quite happily run a binary linked with
> COMMONPAGESIZE set to 4k on a system using 64k pages. COMMONPAGESIZE
> or -z common-page-size is really about where the linker starts the
> data segment, following on from the text segment. It boils down to
> a trade-off between memory pages and disk pages, and the net result of
> increasing COMMONPAGESIZE to 64k for a system running with 4k pages
> is that you'll tend to have bigger on-disk binaries but won't use any
> more memory than with the "proper" 4k COMMONPAGESIZE. On the other
> hand if you really are running with 64k pages, there will be binaries
> where you could save a 64k page of memory if you'd specified the
> proper COMMONPAGESIZE at link time.
> Overall, I think the increased COMMONPAGESIZE is beneficial, so I'm
> happy with the patch.
Since RTEMS uses its own linker command files, this change has no impact
on RTEMS. Otherwise it would be a problem since some chips have about
64KiB of RAM.
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : firstname.lastname@example.org
PGP : Public key available on request.
Diese Nachricht ist keine geschÃ¤ftliche Mitteilung im Sinne des EHUG.
More information about the Binutils