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Re: nasty bug in /usr/sbin/grub-probe

On 4/2/22 03:30, John Paul Adrian Glaubitz wrote:

Hello Dennis!

On 4/2/22 03:34, Dennis Clarke wrote:

I am not so sure about this yet until I can rebuild the required grub
binaries with full debug info. For at least a year ( or more ) I have
seen "really bad things"(tm) happen when I try to make a new initrd on
sparc64. Generally the machine seems to pack up and go away with nary a
single packet out to the world. To look into this problem I use a serial
attached good old 9600 baud console and watch what happens when I try to
do a make install from within the Linux source tree :
(...)
So therefore I think that there is a bug in /usr/sbin/grub-probe and it
really kills the whole "make install" process from within the Linux
kernel source tree or any other way you choose to run it.

Has anyone else seen this ?


This isn't a bug in GRUB but a kernel bug that affects older SPARC machines
like your UltraSPARC IIIi. Unfortunately, no one has had the time yet to bisect
this issue.

But since you seem to have a reliable reproducer, you can start trying to bisect
the kernel to find the commit that introduced this regression.



That will be nearly impossible. I can not even recall when the bug first
appeared or when was the last time that I could run update-grub without
the machine locking up. At least two years now. Maybe three.

Also this is an even older UltraSparc IIi type machine. Really I should
have tossed it out long ago but the next machine I have handy is a
Fujitsu M3000 unit and I thought I had heard it was impossible to get
Linux on such a beast for unknown reasons. Could be myth or rumour but I
thought the M3000 was somehow "special". The larger M4000 seems to be
fine but those are just nasty large beasts to run in a home lab.

Dragging the deep waters looking for that kernel bug will take a lot of
time. Possibly even some luck.


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