Re: TIOCGWINSZ retuns old pty size after receiving SIGWINCH

[Christoph <cr2005@u-club.de>]

Hello list!

This is a follow up of
http://linux.derkeiler.com/Mailing-Lists/Kernel/2008-08/msg08509.html

Summary:
resizing a terminal emulator window results in a lot of misaligned text
on the screen. SIGWINCH signal defective.

It ends with this question and I'd like to contribute some confusion:

> > 2.6.25.9: good
> > 2.6.26-rc1 bad ( +/- 10% of the resizes)
> > 2.6.26.2: still bad ( +/- 10% of the resizes )
> > 2.6.27-rc3: ugly bad ( > 75% of the resizes )
> > linux-next good

> Any other versions to test ?

I got this bug after kernel upgrade from 2.6.25.25 to 2.6.26.5 on my ppc
notebook. That made me wonder. On my x86 desktop I don't had that bug.
I tested:

ppc, notebook
2.6.25.25 ok
2.6.26.5 bug
2.6.26.4 bug

x86, desktop
2.6.26.1 ok
2.6.26.2 ok
2.6.26.3 ok
2.6.26.4 ok !

So I diffed the config of .4 and there is an eye catcher:

ppc: CONFIG_PREEMPT (=> CONFIG_LOCK_KERNEL)
x86: CONFIG_PREEMPT_VOLUNTARY

So, recompiled and tested:

2.6.26.4, x86, CONFIG_PREEMPT => bug
2.6.26.5, ppc, CONFIG_PREEMPT_VOLUNTARY => ok

Hope, this information helps you hunting the bug.

greets

chr