From: Arnd Bergmann <arnd@arndb.de>
To: Adrian Bunk <bunk@stusta.de>
Subject: Re: 2.6.12-rc1 breaks dosemu
Date: Fri, 25 Mar 2005 19:52:31 +0100
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       Arjan van de Ven <arjan@infradead.org>, Ingo Molnar <mingo@elte.hu>
References: <20050320021141.GA4449@stusta.de>
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On S?nndag 20 M?rz 2005 03:11, Adrian Bunk wrote:
> xdosemu 1.2.2 runs fine under 2.6.11.5, but fails under 2.6.12-rc1 with 
> the following error:
> 
> <--  snip  -->
> 
> $ xdosemu 
> ERROR: cpu exception in dosemu code outside of VM86()!
> trapno: 0x0e  errorcode: 0x00000005  cr2: 0xffffff8e
> eip: 0x000069ee  esp: 0xbfdbffcc  eflags: 0x00010246
> cs: 0x0073  ds: 0x007b  es: 0x007b  ss: 0x007b
> Page fault: read instruction to linear address: 0xffffff8e
> CPU was in user mode
> Exception was caused by insufficient privilege

I had the same problem and found out that disabling
address space randomization (echo 0 > 
/proc/sys/kernel/randomize_va_space) solves this
reliably. With randomization enabled, I can start up
dosemu maybe 1 out of 100 times.

I guess the randomization patches changed the mapping
in a way that dosemu did not expect.

 Arnd <><
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