Re: ia64 port needs help in order to be saved

On 05.08.20 14:51, John Paul Adrian Glaubitz wrote:
> Hello Frank!
>
> On 8/4/20 9:04 PM, Frank Scheiner wrote:
>> All kernels used Sergei's configuration adapted to enable network boot.
>>
>> * 4.14.83 vanilla w/o ptrace patch and compiled with "gcc (Gentoo
>> 7.3.0-r3 p1.4) 7.3.0" leads to a reboot after kernel and initramfs are
>> loaded:
>>
>> ```
>> ELILO v3.16 for EFI/IA-64
>> ..
>> Uncompressing Linux... done
>> Loading file AC10027B.initrd.img...done
>> 1,0,0,0 5400006301E10000 0000000000000000 EVN_BOOT_START
>
> I have noticed that such an immediate reboot is also observed with certain
> versions of elilo. For example, the elilo version in Wheezy causes an
> immediate reboot while the version from Squeeze works.

Sure, but this version of elilo works for all my Itanium machines (even
with newer kernels on other machines than the rx2800 i2) - I haven't yet
evaluated GRUB for these machines and hence am conservative or reluctant
to change the boot loader for testing a specific kernel. I don't want to
change too many things.

And the behavior is similar to what Sergei wrote in [1] I think, so I'm
confident that this is not coming from the boot loader, but from using
gcc 7.3.0 w/o ptrace patch.

[1]: https://lore.kernel.org/patchwork/comment/1081244/

> But we're using GRUB anyway. And since unpatched versions of gcc are
> known to produce a buggy kernel, we don't need to test that either.

Ok, I just used what I had available on Gentoo. Emerging a new gcc would
take a lot of time and can also produce repercussions with the rest of
the installed software.

For Debian it was relatively easy to test a newer gcc and that really
makes a difference for 4.14.x kernels.

>
>> * 4.14.83 vanilla w/o ptrace patch and compiled with "gcc (Debian
>> 10.2.0-3) 10.2.0" works and boots Debian GNU/Linux Sid successfully to
>> the login prompt on my rx2800 i2 and also runs stable enough to
>> recompile itself:
>>
>> ```
>> ELILO v3.16 for EFI/IA-64
>> ..
>> Uncompressing Linux... done
>> Loading file AC10027B.initrd.img...done
>> [    0.000000] Linux version 4.14.83vanilla (root@rx2800-i2) (gcc
>> version 10.2.0 (Debian 10.2.0-3)) #1 SMP Tue Aug 4 15:56:40 UTC 2020
>> [...]
>> Debian GNU/Linux bullseye/sid rx2800-i2 ttyS1
>>
>> rx2800-i2 login:
>> ```
>>
>> * The same holds true for 4.14.191 vanilla w/o ptrace patch and compiled
>> with the same gcc.
>>
>> So latest 4.14.x kernels should work w/o the patch on a rx2800 i2 with
>> Itanium 9300 (Tukwila) series processors - if they are compiled with gcc 10.
>
> I'm currently running a 4.14.192 kernel with the ptrace patch. While it doesn't
> crash, I'm seeing a kworker thread with rather high load.
>
> Do you observe that as well?

Not that I know of, but I didn't check activity the whole time. I'll
observe activity next time I fire the machine up.

What I saw on Debian were unaligned memory accesses. But I think that is
common on non-x86 arches.

Cheers.
Frank