Xen devel - Apr 2008 - Xen gdb -- unable to set breakpoints on x86-64 PV linux domU

Hi,

Does gdb on x86_64 work on a recent xen-3.1-testing branch??

I followed the instructions in tools/debugger/gdb/README, to setup a  
gdb session on a x84-64 PV Linux domU. I''m unable to set any  
breakpoints. Similar errors were reported earlier in two e-mail threads:

1. http://lists.xensource.com/archives/html/xen-devel/2006-10/msg00205.html
    - This was in PAE mode. Keir found the problem:
       "Ah, the lookup function is mapping the PTE page with write
permissions.
        That won''t work. I''ll check in a fix."
        I want to verify if my sources includes it. But, I''ve not been
able
        to trace the fix.

2. http://lists.xensource.com/archives/html/xen-tools/2007-05/msg00001.html
    - This was a more recent error report on x86_64. But, no response.

Any tips? More details on the error below.

Thanks,
Shanth

GDB reports:
   (gdb) break schedule
   Breakpoint 1 at 0xffffffff803e2884: file  
include2/asm/thread_info.h, line 63.
   (gdb) target remote 127.0.0.1:9999
   Remote debugging using 127.0.0.1:9999
   [New Thread 0]
   [Switching to Thread 0]
   0xffffffff802063aa in hypercall_page ()
   (gdb) bt
   #0  0xffffffff802063aa in hypercall_page ()
   #1  0x0000000000000000 in ?? ()
   (gdb) c
   Continuing.
   Warning:
   Cannot insert breakpoint 1.
   Error accessing memory address 0xffffffff803e2884: Input/output error.
   Cannot insert breakpoint -2.
   Error accessing memory address 0xffffffff80200000: Input/output error.

Xen hypervisor reports:
   (XEN) mm.c:625:d0 Non-privileged (11) attempt to map I/O space 00000000
   (XEN) mm.c:625:d0 Non-privileged (11) attempt to map I/O space 00000000
   (XEN) mm.c:649:d0 Error getting mfn ee02d (pfn 10622d) from L1  
entry 80000000ee02d125 for dom11
   (XEN) mm.c:649:d0 Error getting mfn ee02d (pfn 10622d) from L1  
entry 80000000ee02d125 for dom11
   (XEN) mm.c:649:d0 Error getting mfn fafff (pfn 5555555555555555)  
from L1 entry 80000000fafff125 for dom11


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On 10/4/08 19:56, "shanth@cs.utah.edu" <shanth@cs.utah.edu>
wrote:
> 1. http://lists.xensource.com/archives/html/xen-devel/2006-10/msg00205.html
>     - This was in PAE mode. Keir found the problem:
>        "Ah, the lookup function is mapping the PTE page with write
> permissions.
>         That won''t work. I''ll check in a fix."
>         I want to verify if my sources includes it. But, I''ve not
been able
>         to trace the fix.
This is changeset 11698 in xen-3.1-testing.hg. It''s an old fix so
you''re
sure to have it.
> 2. http://lists.xensource.com/archives/html/xen-tools/2007-05/msg00001.html
>     - This was a more recent error report on x86_64. But, no response.
Well, I''d need to set myself up with a 64-bit dom0 and a 64-bit domU to
test
this. If it can be reliably reproduced then it can''t be anything that
tricky
to fix I''m pretty sure.

 -- Keir



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