Re: [Xen-devel] Cannot save/migrate domains

[Arthur Bergman <abergman@xxxxxxxxxxx>]

I realize this monologue might be odd, or maybe tiresome. However I am 
trying to resolve this issue so I am digging deeper into the source 
code.
Following the code inside the macro, it seems like

(gdb) p live_mfn_to_pfn_table
$13 = (long unsigned int *) 0x0

so the code that does

live_mfn_to_pfn_table[_mfn]

results in

(gdb) p live_mfn_to_pfn_table[mfn]
Cannot access memory at address 0x66aa0

So it seems to me, in my quick look that

    live_mfn_to_pfn_table =
        xc_map_foreign_range(xc_handle, DOMID_XEN,
                              PAGE_SIZE*1024, PROT_READ,
                              mfn_to_pfn_table_start_mfn );


returns 0

which seems to be a ok value for it to return...

cheers
Arthur


-----
CTO @ Fotango Ltd
+447834716919
http://www.fotango.com/

On 1 Feb 2005, at 17:26, Arthur Bergman wrote:

> And now with debugging turned in libcx.so.2.0
>
> 0x40026868 in xc_linux_save (xc_handle=8, ioctxt=0xbffff8f0) at 
> xc_linux_save.c:516
> 516             if ( 
> !translate_mfn_to_pfn(&pfn_to_mfn_frame_list[i/1024]) ){
> (gdb) bt
> #0  0x40026868 in xc_linux_save (xc_handle=8, ioctxt=0xbffff8f0) at 
> xc_linux_save.c:516
> #1  0x0804d546 in xen_domain_snd (xend=0xbffffb20, io=0x805fbe0, dom=2,
>     vmconfig=0x805f6d8 "(domain (id 2) (name test) (memory 128) 
> (maxmem 131072) (state -b---) (cpu 0) (cpu_time 4.059911993) (up_time 
> 1064.72708416) (start_time 1107281260.96) (console (status listening) 
> (id 17) (domain 2) ("..., vmconfig_n=666, live=0, resource=0) at 
> xen_domain.c:103
> #2  0x0804befb in xfr_save (args=0x805d87c, state=0xbffffa50, 
> xend=0xbffffb20, file=0x805f9b8 "/tmp/bla") at xfrd.c:774
> #3  0x0804c8d3 in xfrd_service (args=0x805d87c, peersock=6, peer_in=
>       {sin_family = 2, sin_port = 44804, sin_addr = {s_addr = 
> 16777343}, sin_zero = "\000\000\000\000\000\000\000"}) at xfrd.c:950
> #4  0x0804ccf4 in xfrd_accept (args=0x805d87c, sock=2) at xfrd.c:1024
> #5  0x0804ce01 in xfrd_select (args=0x805d87c, listen_sock=2) at 
> xfrd.c:1054
> #6  0x0804d0f1 in xfrd_main (args=0x805d87c) at xfrd.c:1210
> #7  0x0804d273 in main (argc=1, argv=0xbffffe24) at xfrd.c:1264
>
> (gdb) p i
> $2 = 0
> (gdb) p pfn_to_mfn_frame_list[i/1024]
> $3 = 105128
> (gdb) p &pfn_to_mfn_frame_list[i/1024]
> $4 = (long unsigned int *) 0xbfffcea0
>
> Anything in particular I should start looking at?
>
> -----
> CTO @ Fotango Ltd
> +447834716919
> http://www.fotango.com/
>
> On 1 Feb 2005, at 17:14, Arthur Bergman wrote:
>
> > And slightly bit more..
> >
> >
> > gdb xfrd
> > (gdb) set follow-fork-mode child
> > (gdb) run
> > Starting program: /usr/sbin/xfrd
> >
> > Program received signal SIGSEGV, Segmentation fault.
> > [Switching to process 13699]
> > 0x40026808 in xc_linux_save () from /usr/lib/libxc.so.2.0
> > (gdb) bt
> > #0  0x40026808 in xc_linux_save () from /usr/lib/libxc.so.2.0
> > #1  0x0804d546 in xen_domain_snd (xend=0xbffffb20, io=0x805fbe0, 
> > dom=2,
> >     vmconfig=0x805f6d8 "(domain (id 2) (name test) (memory 128) 
> > (maxmem 131072) (state -b---) (cpu 0) (cpu_time 4.030152025) (up_time 
> > 611.702224016) (start_time 1107281260.96) (console (status listening) 
> > (id 17) (domain 2) ("..., vmconfig_n=666, live=0, resource=0) at 
> > xen_domain.c:103
> > #2  0x0804befb in xfr_save (args=0x805d87c, state=0xbffffa50, 
> > xend=0xbffffb20, file=0x805f9b8 "/tmp/bla") at xfrd.c:774
> > #3  0x0804c8d3 in xfrd_service (args=0x805d87c, peersock=6, peer_in=
> >       {sin_family = 2, sin_port = 44292, sin_addr = {s_addr = 
> > 16777343}, sin_zero = "\000\000\000\000\000\000\000"}) at xfrd.c:950
> > #4  0x0804ccf4 in xfrd_accept (args=0x805d87c, sock=2) at xfrd.c:1024
> > #5  0x0804ce01 in xfrd_select (args=0x805d87c, listen_sock=2) at 
> > xfrd.c:1054
> > #6  0x0804d0f1 in xfrd_main (args=0x805d87c) at xfrd.c:1210
> > #7  0x0804d273 in main (argc=1, argv=0xbffffe24) at xfrd.c:1264
> > (gdb)
> >
> > I guess I am going to need to recompile with debugging on.
> >
> > Cheers
> > Arthur
> >
> > -----

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