Re: [2/2] 2.6.22-rc4: known regressions v3

From: Mark Fortescue
Date: Thu Jun 14 2007 - 10:57:59 EST



Benh's ptep_set_access_flags() patch needs to be applied in order to get anyware with sun4c for all kernels >= linux-2.6.15. If not applied, you will be lucky to get sash running as your init and even that will have very limitit capabilities before it locks up the processor (power up reset required).

It has been applied to both the kernels I used for testing so this problem is independent of the ptep_set_access_flags patch but that does not mean that it is not a related issue.

I will try to get some testing done over the weekend to narrow down when the random illegal instructions first occour.

If I start with 2.6.21 then if that is OK, then I should be able to narow the issue down without too much trouble. If it is between 2.6.20 and 2.6.21 then it will be a right pig as there are a large number of commits that don't compile for sun4c between these two. What I am hoping is that it occours in the 2.6.22-rc2 as per the x86_64.

I am going to have to put a 'reset' button onto my test system as power up resets are bad news on this old hardware and almost all kernel failures result in a processor lockup. I have even had to make BUG reports 'panic' as thoes that I have during kernel fault location had are terminal to a sun4c (they cause a processor lockup).

Regards
Mark Fortescue.

On Thu, 14 Jun 2007, William Lee Irwin III wrote:

On Thu, Jun 14, 2007 at 11:30:25AM +0100, Mark Fortescue wrote:
They apear as soon as simpleinit starts up. Somtimes I get to a login
prompt before seeing any. Other times, commands in the simpleinit rc
script fail.
They do apear to be random. If a command failes, you re-run the command
and it is OK. Commands seen to fail are basic (depmod, rm cat ..).
The test I did use the same binaries with both the OK and problem kernels
so it is not a change to the application code, it is definatly a kernel
issue.

This sounds like it may be addressed by benh's ptep_set_access_flags()
fixes. Those fixes are still in -mm, hopefully to hit mainline by 2.6.22.


-- wli

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