Re: Can't set break points with Linux guest in PAE mode

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Oct 04, 2006 at 04:54:18PM -0700, Randy Thelen wrote:
> Folks --
> 
> One more time with the PAE request, this time I've brought up the  
> Linux kernel w/ a very recent version of Xen.  (Just yesterday I  
> pulled and updated my hg tree.)  I still can't set breakpoints within  
> the guest domain:
> 
> # gdb vmlinux
> GNU gdb 6.4-debian
> <...>
> (gdb) target remote roti.lab.netapp.com:9999
> Remote debugging using roti.lab.netapp.com:9999
> [New thread 0]
> [Switching to thread 0]
> 0xc0100000 in startup_32 ()
> (gdb) b *0xc0100000
> Breakpoint 1 at 0xc0100000
> (gdb) s
> Single stepping until exit from function startup_32,
> which has no line number information.
> Warning:
> Cannot insert breakpoint 1.
> Error accessing memory address 0xc0100000: Input/output error.
> 
> (gdb)
> 
> 
> My RS232 Xen console looks like:
> 
> xenbr0: port 3(vif7.0) entering learning state
> xenbr0: topology change detected, propagating
> xenbr0: port 3(vif7.0) entering forwarding state
> xenbr0: port 3(vif7.0) entering disabled state
> device vif7.0 left promiscuous mode
> xenbr0: port 3(vif7.0) entering disabled state
> device vif8.0 entered promiscuous mode
> (XEN) DOM0: (file=mm.c, line=1688) Bad type (saw 28000001 != exp  
> e0000000) for mfn 96efe (pfn 573)
> (XEN) DOM0: (file=mm.c, line=606) Error getting mfn 96efe (pfn 573)  
> from L1 entry 0000000096efe027 for dom8
> (XEN) DOM0: (file=mm.c, line=1266) Bad get_page_from_l1e(): pl1e =  
> fefa6a30, nl1e = 96efe027, ol1e = 0, gl1mfn = d8538
> (XEN) DOM0: (file=mm.c, line=2283) Could not modify L1 entry: va ==  
> fefa6a30, l1e == 96efe027, mfn == d8538
> 
> (I've added the two MEM_LOG() calls at line 1266 and 2283.)
> 
> Any ideas where I should begin looking?  Or is PAE support languishing?

gdb + PAE may not get much testing, but PAE kernels themselves certainly
are mainstream. Fedora Core 5 recently started providing PAE kernels in
addition to non-POAE ones, and Fedora Core 6 / RHEL5 will only support PAE
on i386, so there's plenty of use there. Prety sure SLES also uses PAE
kernels. 

Regards,
Dan.
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