Old PowerMac G5 2-socket/2-cores-each: head -r368820 kernel reports: bus_dmamem_alloc failed to align memory properly

[Dennis Clarke]

On 12/21/20 11:03 PM, Mark Millard wrote:
> 
> 
> On 2020-Dec-21, at 19:02, Dennis Clarke via freebsd-ppc <freebsd-ppc at freebsd.org> wrote:
> 
>> On 12/21/20 9:58 PM, Dennis Clarke via freebsd-ppc wrote:
>>> On 12/21/20 9:27 PM, Mark Millard via freebsd-ppc wrote:
>>>> I'm upgrading from head -r365932 to -r368820 and on the first
>>>> boot -s with the new (non-debug) kernel I saw that bus_dmamem_alloc
>>>> was reporting based on:
>>>>
>>>
>>> Do you know if there is a workable installer image for anything recent?
>>> My powermac quad has been dead for a month and I just want to do a
>>> fresh re-install with ZFS and all the CURRENT goodness.
>>>
>>>
>>>
>>>
>>
>> Sorry that was a dumb question.
>>
>> I see :
>>
>> https://download.freebsd.org/ftp/snapshots/powerpc/powerpc64/ISO-IMAGES/13.0/
>>
>> I will give that a try.
> 
> 
> Not a dumb question. PowerMacs have been problematical for as long as
> I've been trying FreeBSD on them (FreeBSD 10+ basically). That includes
> examples of of install time problems.
>

Well, I had to give it a try :

https://beta.genunix.com/freebsd/ppc64/power_mac_quad_freebsd_13_current_17_dec_2020_fail.png

So that is the most recent installer image there. Not sure what fails.

I had this old powermac running FreeBSD 12.x and CURRENT last year. I
even chased after a pile of little bugs and recall working with Justin
Hibbits to get boot going smoothly with all the fans being correct etc
etc. Things have changed a lot in a year.  I guess a Power9 server is
really needed. Or maybe Power8 perhaps.

> I'm not aware of any unpatched, modern FreeBSD that well-operates any old
> PowerMac that I have access to (64 bit or 32 bit). But I've not done a
> from-scratch install (via a installer image) in years so I do not know what
> the issues are with that stage these days. My understanding is folks
> have been disabling SMP support so only 1 thread run in order to avoid some
> of the problems for multi-socket/multi-core PowerMacs.

Right. I thought we had that fixed last year?

Bug 233863 - Various PowerMac G5 models may require kern.smp.disabled=1
and must set usefdt=1 which causes net interface reorder

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233863

   also

Bug 238730 - r349985 on ppc64 IBM 970MP PowerMac G5 sys/dev/bge/if_bge.c
must move the device_get_devclass(bus)

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=238730

Bug 233579 - ppc64 r341455 will panic on boot with usefdt=1
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=233579

I think you and I have gone back and forth on these and others and for a
while there we had it working fairly well. With ZFS also.


> 
> Other notes:
> 
> As far as I know, 32-bit powerpc for old PowerMacs still has the kernel
> gradually zeroing out user-space pages, even for single-socket/single-core
> 32-bit PowerMacs. So I run 32-bit via a chroot on a 64-bit system: the
> 64-bit kernel does not have this specific problem. (I seem to remember
> that there was a different boot failure last I tried 32-bit, but I do not
> remember any detail at this time.)
> 
> There are other kernel problems as well (64-bit and 32-bit), but I'll not
> get into them here.
> 

Well I guess I have to pick my battles here and maybe move onwards with
the RISC-V goodness wherein I have been in touch with Mitchel Horne and
I have CURRENT running really well with ZFS. Well, on qemu of course.
However I can not do a buildworld. That jsut fails in the LLVM/Clang
world and it looks to be a LLVM/clang bug. Regardless the old old Apple
PowerMac may be a doorstop now. A good looking shiney door stop but not
really workable.  Even Debian Linux fails to install these days.

> The best of the old PowerMac's that I've had access to finally ended up
> with overheating from the cooling system not working correctly any more.

I had not seen that here with mine and I have four of them. I take parts
from one to the other just to keep one running well.

> The previously next-best does not have all the memory slots working. That
> is the last 2-socket/2-cores-each G5 that I have access to. So one of
> these day's I'll be joining others that no longer have access to such.

I feel that day is coming soon for me also.

> With the degree of my time preferences, I'm not sure if I'd use the old
> PowerMacs without the faster one to do builds on. (I tend to cross
> build the systems, only self-hosting on rare occasion. But ports
> I build on the Fastest PowerMac that I have access to.)
> 

Well if there was such a thing as a reasonable serial console on these
things then I would easily grant you ssh access to a KVM switch and to
the serial console. Debugging anything via camera and the graphical
console is a real pain.

Thank you for the detailed reply and I will flip a coin or two and maybe
just retire these shiney old monsters.  They use a pile of power also :)

That just leaves the Sun SPARC servers in my life as the most stable
long term reliable monsters that I have. Sadly Oracle makes like hell
and not much runs on the newer Fujitsu machines that I have. Looks like
some investment in RISC-V may be reasonable for next year.


-- 
Dennis Clarke
RISC-V/SPARC/PPC/ARM/CISC
UNIX and Linux spoken
GreyBeard and suspenders optional