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Re: gdb: Error accessing memory address 0x4000af50: Input/outputerror.
- From: Andrew Cagney <cagney at gnu dot org>
- To: "Grigorio V. Moshkin" <grigorio at garant dot ru>
- Cc: gnu at gnu dot org, gdb at sources dot redhat dot com
- Date: Tue, 08 Feb 2005 11:29:51 -0500
- Subject: Re: gdb: Error accessing memory address 0x4000af50: Input/outputerror.
- References: <200501141840.49315.grigorio@garant.ru>
Grigorio V. Moshkin wrote:
Hello!
Try cating /proc/PID/maps and see what's at that address. I suspect
you'll find that it's the ``vsyscall page'' and your kernel letting the
debugger see that pages contents.
That's a kernel bug - GDB is being asked to do the equivalent of fly blind.
Andrew
On my Mandrake 9.1 linux and Pentium-4 / 2GB RAM machine ANY debuggers CAN NOT
debug ANY application due to this email subject. The subject error occurs
always I try to insert breakpoint.
Debuggers tested:
gdb 5.3-22mdk, gdb 6.3 compiled from sources, ups 3.38 beta2 from sources.
Kernel tested: various 2.4.21 with himem config on/off as gone as binaries
from Mandrake, and compiled from Mandrake sources. Also I tried to load as
minimum kernel modules as possible.
Note, on my home machine amd-k6-2 / 220M all works fine!
What's the reason of such an error?
P.S. I have read mailing lists. Some people report similar 'bug'. But detailed
research of their texts show this bug was rare enough and appeared due to
various exotic reasons such as 'debugging a 32-bit application by 64-bit
gdb'. I thrust my case is trivial and does not depend on given debugger. But
I really cant' imagine what's the reason?
Please replay me directly if possible, not to gdb mailing list only.