Re: ia64 port needs help in order to be saved

On 04.08.20 15:12, Frank Scheiner wrote:
> On 04.08.20 13:20, John Paul Adrian Glaubitz wrote:
>> The kernel has this configuration from Sergei [1] and the ptrace patch
>> from
>> the Gentoo kernel, otherwise it's a vanilla upstream kernel 4.14.83.
>>
>> I cannot say yet which particular change fixes the problem, but I'm
>> confident
>> I will be able to figure that out. If you want to test yourself, you may
>> try 4.14.83 from the stable branch [2] with Sergei's configuration but
>> without
>> the ptrace patch.
>
> Yeah, I'll give that a try.

Ok, I have a few results:

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

***********************************************************
* ROM Version : 01.93
* ROM Date    : Wed Sep 12 22:10:03 PDT 2012
***********************************************************
```

Which makes sense, as [4] explicitly speaks of issues with gcc 6.4.0,
7.2.0 and the latest gcc 8 at that time which are worked around by the
patch.

[4]: https://lore.kernel.org/patchwork/comment/1079097/

* 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.

>> My wild guess is that's the ptrace patch that fixes the problem.
>
> Yeah, I think so, too, but will check that now, to be sure.

I haven't tested anything newer than the latest 4.14.x and also no
kernels with Debian patches, but maybe the newer gcc will also make a
difference for later kernel versions.

Cheers,
Frank