[Crash-utility] kdump format may be updated

[Dave Anderson]

Kazuo Moriwaka wrote:

> Hello,
>
> A new release of the kexec/kdump patches for x86 xen have recently
> been posted to the xen-devel mailing list:
>
> http://lists.xensource.com/archives/html/xen-devel/2006-10/msg00611.html
>
> To simplify the kernel and hypervisor code, the kdump format may be
> changed in future releases. The idea is to make the kernel and
> hypervisor code as simple as possible and put more knowledge into the
> tools.
>
> If you have any comments or recommendations now is a good time to step
> up and give feedback to the thread on xen-devel.
>

This message should be posted to the "fastboot" mailing list, as they
are the ones that driving the kexec/kdump development.  I'll forward
this to our internal kexec-kdump-list as well.

In any case, with respect to how this affects the crash utility, this
section appears to be the key change, in the x86 find_dom0_cr3()
function:

+       for_each_vcpu ( d, v ) {
+               if ( test_bit(_VCPUF_down, &v->vcpu_flags) )
+                       continue;
+               buf = (uint32_t *)per_cpu(crash_notes, v->processor);
+               if (!buf) /* XXX: Can this ever occur? */
+                       continue;
+
+               memcpy(&note, buf, sizeof(Elf_Note));
+               buf += (sizeof(Elf_Note) +3)/4 + (note.namesz + 3)/4 +
+                       (note.descsz + 3)/4;
+
+               /* XXX: This probably doesn't take into account shadow mode,
+                * but that might not be a problem */
+               cr3 = pagetable_get_pfn(v->arch.guest_table);
+
+               buf = append_elf_note(buf, "Xen Domanin-0 CR3",
+                       NT_XEN_DOM0_CR3, &cr3, 4);
+               final_note(buf);
+
+               printk("domain:%i vcpu:%u processor:%u cr3:%08x\n",
+                      d->domain_id, v->vcpu_id, v->processor, cr3);
+       }
+}

As we discussed before, it would have been preferable in my
opinion to have the starting-point mfn value for all the domains,
thereby making the dumpfile usable for all domains instead of
just dom0.  But I will be happy with at least getting this change
in place so that crash can be used directly on the xen dumpfile
for dom0 analysis without having to run it through some other
utility.

However, I don't see the analogous changes for x86_64.
Was that left out by mistake or on purpose?

BTW, like the original patch from months ago, the spelling
of the ELF note is still incorrect, i.e., it should be
"Xen Domain-0 CR3".

Thanks,
  Dave

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