Re: New architecture ppc64el on Debian
On 09/23/2013 11:43 AM, Lennart Sorensen wrote:
> On Sun, Sep 22, 2013 at 06:08:12PM +0900, Joel Rees wrote:
>> I suppose I'm not really one privileged to express these reactions, but I
>> tend to be a loose cannon sometimes.
>>
>> ???
>>
>> (Checking my calendar. Nope, I haven't suddenly slipped back to the early
>> 1990s.)
>>
>> (Still puzzled.)
>
> Well I see patches for linux on powerpc in little endian mode (it is software
> selectable on most powerpc chips as far as I know) were submitted in August of
> this year, and patches to qemu were done around the same time to support
> emulating little endian mode powerpc.
Right. Kernel, toolchain and qemu had their patches already to enable ppc64 little
endian.
>> Not that it's my problem to worry about at all.
>>
>> My impression is that the sooner you can have the new target hardware
>> available to donate to the build farms the better, as someone else has also
>> mentioned.
>
> Hardware has existed for years. It just isn't the mode if is normally used
> in.
Right. I am also working in a way to provide three machines to the Debian server
farm. Unfortunatelly I still don't have a date, but definitely we would like to
have machines on Debian server farm.
So, we will not need to change ppc64 machines that Debian has for now.
>> You've had several people hint. I've hinted, too. It seems like there is
>> something that needs to be explained.
Right. Since Power processor can run in little endian and big-endian, there are
some advantages of using PowerPC in little endian mode, as Lennart told.
Moreover, it ease the process of porting from x86 to ppc64, since porting process
doesn't need to care about endianess.
>>
>> Why the fuss?
>>
>> It's not like endian-ness is a barrier to performance. Is there some
>> Intel-fomented rumor floating around data centers with BOFH admins, that the
>> endian-ness is the Power architecture's Achilles' heel or something?
>>
>> Hmm. I suppose it might have something to do with graphics chips which seem
>> to be all x86-oriented and are now being used as dedicated numeric array
>> processors, per this commentary in LWN: <http://lwn.net/Articles/408845/>.
>> That's going the way of the dodo in about three to five years, but I suppose
>> there may be some purpose in reactionary marketing now.
>
> It does appear to have to do with support for graphics cards that were designed
> to assume little endian. Given x86 and arm seem to run almost exclusively in
> little endian mode these days (not that x86 even has an option not to unlike
> arm), perhaps IBM has decided that to get better performance and support for
> running high performance software using graphics cards, it makes sense to get
> little endian support going in linux for their big powerpc boxes.
>
>> Well, anyway, the devs are the ones to make up their minds on how much
>> resource to put in on this, so I suppose I should shut up. But it sure seems
>> like Intel leads a lot of useless market churn. If the predictions about
>> global climate change turn out to be true, when the amount of excess waste
>> heat generated by using x86 in infrastructure is calculated, do we sue Intel
>> for the part it plays in wasting the earth through excess hardware turnover
>> and energy use?
>
> Well you could always complain about IBM choosing the x86 in the first place,
> or complain that people bought IBM's machines in the first place at a time when
> lots of other machines were using m68k chips instead.
>
> Seems a bit late to fix it now though. So perhaps this is a sensible move on
> IBM's part.
>
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