Re: Debian kernel boot failure on Alpha [was Re: systemd FTBFS]
Hi Michael,
ooops, looks like I have to correct myself. :-( The Debian v4.8 and v4.9
(up to 4.9.18) SMP kernels do not successfully boot on my AlphaStations
200 and 255 - at least not fully, they do start though. I didn't test
the `agp=off` kernel command line option on the AlphaStations before
finishing my last email, but assumed it will just make them work, as it
didn't do any harm when using it on the PWS 500au. :-/
It looks like it only works until or after the agpgart message appears.
But then it hangs. And when using `agp=off` it hangs just before the
agpgart message would have appeared. Maybe this is related to the commit
you mention at the end, but that reads like it should affect all my
other Alpha machines, too.
I have seen the AlphaStation 255 working until the IP auto configuration
with the v4.8.x (and the v4.9.18 one just today) SMP kernel one single
time each, but the IP auto configuration didn't succeed, because the NIC
couldn't or didn't accept the IP address given by the DHCP server.
After several tries it looks like it only gets to the IP auto
configuration for the first boot after the machine was powered off for a
longer time. So could be a heat issue, too...
But even when it reaches the IP auto configuration it does not succeed,
though I now also use an additional NIC as described below to avoid the
usage of the de2104x based one during IP auto configuration.
I think the IP auto configuration problem is related to the de2104x
driver, as I have had the same problem on my AXPpci33 with a DE435 NIC.
But there I could workaround it by using the DE435 just for netbooting
the combined kernel and initrd image and using a second NIC for mounting
the NFS root FS during kernel boot. The AXPpci33 does not show the other
problem of the AlphaStations and works just like the PWS 500au and
AlphaServer DS20E. But the AlphaStations nearly always start to hang
before reaching the IP auto configuration, even if using another NIC in
addition.
On 04/10/2017 10:38 AM, Michael Cree wrote:
[...]
There were some messages about
enabling BWX (starting with [1]), but as it should still work with EV56 when
enabled I wondered if my problems were related at all.
[1]: https://lists.debian.org/debian-alpha/2014/09/msg00000.html
Mid of 2015 you wrote on [2] that you haven't yet enabled BWX,
I've managed to switch the defaults in gcc in a test run and started
a local repository rebuild to test it but it exposed a nasty bug in libc
so I couldn't continue to test. That took some time to fix and I never
returned to exploring switching Debian Ports to using BWX. My feeling is
that we should in fact do that considering that the i386 arch recently
dropped support for Intel chips that are more recent than the old-time
Alpha cpus we still support!
Yeah, but those old-time Alpha CPUs are so much more interesting than
any i386 based CPU, don't you agree? :-D
Think about the implications of using BWX: I don't know for sure what
Alpha machines other people have available, but I assume that using BWX
would lock out a big part of the machines that are available to
hobbyists nowadays (everything pre EV56). Which would also lock out a
lot of people that could test things on their machines in the past and
at least help in this respect. So I'm afraid this change could shrink
the Debian Alpha user base considerably unless people manage to procure
newer Alpha gear, which might prove difficult. I'm afraid with less
machines supported by Debian GNU/Linux it will be even easier to give up
on the Alpha architecture completely in the future.
On the other hand I understand your arguments in [1]. I am no kernel
developer so I can't offer you my help in this regard to spread the
load, but I can offer to test things on my Alpha machines if it helps.
And keep in mind that Debian Alpha is still alive despite BWX not used
since more than two years. :-)
I'm thankful that I can still run Debian GNU/Linux on my Alpha machines
nowadays and I'd love to also keep the older machines running with
Debian GNU/Linux in the future.
But that of course doesn't buy you extra time for maintaining Debian
Ports. :-/
[1]: https://lists.debian.org/debian-alpha/2014/09/msg00000.html
Until recently I didn't have a reason to also try the SMP variant of the
v4.x Linux kernels, but now that I have a DS20E and had the same problems
with the generic Linux kernel v4.x from Debian I also tried the SMP variant
on it.
And the SMP variant of the v4.x kernel just works (tested with
"4.8.0.2-alpha-smp", "Debian 4.8.11-1" from 2016-12-02 to be exact).
Now that it is interesting! The SMP kernel also boots on my XP1000.
The only downside to using an SMP kernel is extra allocations of per-cpu
data structures, and the loss of some optimised code that eject SMP
barriers.
Well, I was happy that it ran at all on what I have available - except
for the AlphaStations of course - so I'm fine with some downsides as
long as it runs.
I would be wary of using the Debian 4.9 kernel for any serious work on
Alpha. I presume it still has commit
0784672d05684de901fc2aa56150d7ea9a475a2d which leads to random
segfaults in user space on Alpha (and the occasional kernel OOPS).
I didn't see a single crash on my DS20E so far and since today I'm using
v4.9.18. I'll see what happens during a kernel compilation.
Cheers
Frank
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