RFC: Page size on PPC/PPC64 builders

[Josh Boyer]

On Sun, 02 Mar 2008 18:46:38 -0500
Tom Lane <tgl at redhat.com> wrote:

> David Woodhouse <dwmw2 at infradead.org> writes:
> > I already see people who should know better complaining about how
> > building for PPC is 'painful' -- and that kind of attitude has
> > contributed to the idiocy of letting 'secondary architecture' builds
> > fail _without_ aborting the main build. I don't want to make matters
> > worse by increasing the perception that building for PPC is hard.
> 
> I've used many non-Intel arches for long enough to not particularly
> worry about one versus another.  However, it took me darn near two
> months to puzzle out the mysql bug that started this thread, and that
> was way too painful.  The problems I see that we need to work on are:
> 
> 1. It's impossible to reproduce the Koji build environment accurately
> without access to PPC64 hardware; widely available stuff like Apple
> Macs isn't PPC64 and won't show page-size-related problems.

Um, Apple G5's are ppc64.  So are PS3s.  I'll grant that PS3s aren't
massively powerful boxes due to the limited amount of DRAM, but they
can build packages just fine.

> 2. There is pitifully little opportunity for Fedora developers to
> get at such hardware.  As far as I've found out, there is exactly
> one PPC64 machine available, its location is documented nowhere
> public (eventually I found out that the magic incantation is "ask
> David Woodhouse"), and it's down at the moment.

There have been offers from people other than David.

> 3. It was not at all obvious that the problem stemmed from changing
> the build farm machines' underlying kernels from RHEL4 to RHEL5.
> I wasted a great deal of time on the assumption that I was looking
> for a consequence of a recent rawhide change, when in fact there was
> no such change. 

This I won't really argue with.  However I believe the 64KiB page size
_was_ mentioned to you the first time you posted here about it.

https://www.redhat.com/archives/fedora-devel-list/2008-January/msg00813.html

> Next time we make a change in the buildfarm's underlying kernels,
> I respectfully suggest that that be treated as forcing a mass
> rebuild, just like we do when there are other toolchain changes.
> If I'd seen the breakage first occur in a context like that, it
> would have been much clearer what to look for.

I don't agree with that.  The builders pick up regular kernel updates
for things like security issues, etc. all the time.  Rebuilding
for those is a waste of time.

Perhaps you meant when major change in the kernel is made.  That I
might agree with more, but I'm not entirely convinced.

> As for the other points, if we can't provide (and document) the
> ability for developers to test on a secondary arch, that arch
> needs to be removed from Fedora completely.  It's useless to
> expect developers to magically fix things they can't debug.

That's horseshit.  Complete and utter horseshit.  If the primary
package maintainer doesn't care about a particular secondary
architecture then it's no skin off their nose to simply ignore it.  The
secondary architecture team will pick it up.  That's part of the very
definition of what a secondary architecture is.  There is absolutely no
damn reason to remove it from Fedora completely.

PPC is not a secondary architecture at this time, so perhaps
that's where you are confused.

josh