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List:       xen-devel
Subject:    Re: [Xen-devel] pdb missing files?
From:       "Jonathan M. McCune" <jonmccune () cmu ! edu>
Date:       2005-09-30 21:11:17
Message-ID: 433DA9F5.6060609 () cmu ! edu
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Hi Kip,

Yes, that's exactly my line 394.

And, just for completeness,

root:05:10 PM:root $ ./gdbserver-xen 127.0.0.1:9999 --attach 10
dom0 op failed: No such process
Cannot attach to domain 10: Illegal seek (29)

Thanks,
-Jon


Kip Macy wrote:

>>The next obstacle is that gdbserver-xen is segfaulting upon connection
>>from gdb in dom0. Again, this works great with an unmodified domU. You
>>asked me to give the output from the two different runs of gdbserver-xen.
>>    
>>
>
>
>I actually meant when you gave it an invalid domain id, but that isn't a key
>issue ...
>
>
>#0 0x40021fb4 in map_domain_va () from /usr/lib/libxenctrl.so.3.0
>  
>
>>(gdb) bt
>>#0 0x40021fb4 in map_domain_va () from /usr/lib/libxenctrl.so.3.0
>>#1 0x4002268a in xc_ptrace () from /usr/lib/libxenctrl.so.3.0
>>#2 0x0804cb27 in linux_read_memory (memaddr=0, myaddr=0xbff5ab50 "",
>>len=8)
>>at ../../../gdb-6.2.1/gdb/gdbserver/linux-xen-low.c:394
>>#3 0x0804bd41 in read_inferior_memory (memaddr=The value of variable
>>'memaddr' is distributed across several
>>locations, and GDB cannot access its value.
>>    
>>
>
>
>That is a rather strange place for it to be blowing up. In the past there
>were cases where it would blow up in xc_ptrace when it tried to dereference
>an address that had not been successfully mapped to. In principle using
>alloca could bite you if len were so long that you ran off your stack, but
>you have a small stack and you're only reading 8 bytes. I'll see if I can
>determine any more by spelunking at the assembly level.
>
>Just to confirm that I'm looking at the same code, is your line 394:
>
>buffer[i] = myptrace (xc_handle, PTRACE_PEEKTEXT, inferior_pid,
>(PTRACE_ARG3_TYPE) addr, 0);
>  
>

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