ppc32 on Xserve?

[Milton Miller]

On Fri Dec 23 23:33:24 EST 2005, Jan Schukat wrote:
>
> Hello,
> I got myself an Xserve G5 Single Processor, and want to put a Debian 
> on it, since that is what I have most experience with (and sofware and 
> performance).
> But I still have pretty little experience with ppc hardware, so that 
> could become a catch.
> I have a Debian on my PowerBook and have a pretty customized (minimum 
> components, no initrd, no sound, no graphics etc.,  as much as 
> possible compiled in) own kernel running there.
> But my time to fiddle on my Xserve is somewhat limited, since it is an 
> office where I have a permanent connection and own IP. So I want to 
> prepare as much as possible before going there. And the main thing to 
> prepare is have a prepare a proper kernel-package, that won't let me 
> down when I put it on there.
>
> So here finally my two questions:
>
> 1. I haven't found a kernel_config as a place to start with 
> customizing, can anyone be so kind and point me to one?

I would guess the ARCH=powerpc g5_defconfig should be a good starting 
place.  (This assumes something like recient upstream 2.6.15-rc6 or 
so).

> 2. Since I only have 1GB memory, I figured it would be a waste to use 
> 64bit. But do the SATA/RAID/Thermal/Netweork drivers work with 32bit? 
> I won't need wireless.

The current 64 bit PowerPC architecture has several significant 
differences for kernel programming compared to the 32 bit one.  While 
this does not affect drivers, it does affect the mmu code and the early 
assembly, and even the order in which we call some of the early bringup 
functions.

For that reason, to run on a G5 you need to use a 64 bit kernel.[1]

You should still be able to use the 32 bit userland you are familiar 
with.  Current Debian includes the biarch compiler that should allow 
you to compile 64 bit kernels.

Since you said your fiddle time is limited, to check your 
configuration, you might consider building a test kernel with similar 
features (just changing the cpu type and checking that the mac feature 
stuff is re-enabled) on your PowerBook.

[1] Yes, there was support put back in briefly to run g5 in ARCH=ppc, 
but that has been unmaintained and is expected to disappear durng the 
merge into powerpc.

> Finally, if anyone has anything additional to say, like things I 
> should take care of and that inexperienced with the hardware an easily 
> break, that would be appreciated too.

I don't have a lot of expericence with G5 processors, just other 64 bit 
ones.  Therefore I can't comment on system issues.  And while i have 
used Debian quite a bit, I have let ohters administrate it.

One utility you might look for is the "ppc" utility that changes the 
uname returned to be ppc instead of ppc64.  Sometimes that lets 
packages install that otherwise think they are not on the right 
architecture.  Unfornately I am not sure where to obtain it.

> Once I have my System running there, I will definetely put up a page 
> with my experiences. And I'm also willing to be (ab)used for newest 
> patch testing ;)
>
> Regards
>
> Jan

Hope this helps,
milton