Re: 2.6.12-rc1 breaks dosemu

[Arnd Bergmann <arnd@arndb.de>]

On Sünnavend 26 März 2005 09:18, Bart Oldeman wrote:
> On Sat, 26 Mar 2005, Arjan van de Ven wrote:
> 
> > > eip: 0x000069ee  esp: 0xbfdbffcc  eflags: 0x00010246
> >
> > hmm interesting. Can you check if at the time of the crash, the esp is
> > actually inside the stack vma? If it's not, I wonder what dosemu does to
> > get its stack pointer outside the vma... (and on which side of the vma
> > it is)

The esp value is always slightly below the stack vma and above ld.so.
Running it a few times gives 

stack VMA         crash esp
bfc8f000-bfca4000 bfc5ffcc  
bffa0000-bffb7000 bff5ffcc  
bfe0c000-bfe23000 bfdbffcc  
bf7ff000-bf814000 bf7bffcc  
bfaa9000-bfabe000 bfa5ffcc  
bfaa9000-bfabe000 bfa5ffcc  
bffc5000-bffda000 bff7ffcc  
bfba9000-bfbbf000 bfb5ffcc  
bf865000-bf87b000 bf81ffcc  
bfe7d000-bfe92000 bfe3ffcc
...  
bff9f000-bffb4000 bff5ffcc  
bfc73000-bfc89000 bfc3ffcc
bffe3000-bfff8000 -> works

> To Arnd:
> 
> Another thing you should probably do is to build dosemu with debug
> information, and then look into ~/.dosemu/boot.log after it crashes.
> That will give you the contents of /proc/self/maps, a gdb backtrace and
> various other goodies.
> 
> I've checked it myself but can't reproduce, neither with plain dosemu
> 1.2.2 nor with current CVS.

I'm using the dosemu-1.2.1-3 binary that currently comes with debian
sarge, and would prefer not having to build a new dosemu. As far as
I can tell, the command.com that is started belongs to freedos, not
comcom.
The crash however does happen shortly after the command.com file
is opened.

 Arnd <><