At 12:13 AM +0900 9/19/09, Hideki EIRAKU wrote:
From: Pieter de Boer <pie...@thedarkside.nl>
Subject: Protecting against kernel NULL-pointer derefs
Date: Tue, 15 Sep 2009 10:03:48 +0200
- Are there unwanted side-effects of raising VM_MIN_ADDRESS?
Mapping at address 0x0 is needed by some softwares using vm86 mode.
For example, emulators/doscmd uses vm86 mode to emulate an old DOS
environment. In this case, the address 0x0 - 0x3ff is used for an
interrupt vector of emulated DOS world. If VM_MIN_ADDRESS is not
zero, doscmd doesn't work. vm86 mode is in 32bit i386 architecture
only, not in amd64 or other architectures.
Could we:
a) alter those programs so they didn't need that vector in page 0?
or
b) provide some system call or other facility which would allow
*that* process to use page 0?
--
Garance Alistair Drosehn = g...@gilead.netel.rpi.edu
Senior Systems Programmer or g...@freebsd.org
Rensselaer Polytechnic Institute or dro...@rpi.edu
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