----- "Feng LI" <funglee@xxxxxxxxx> wrote:
> Hey Dave,
>
> I attached the crash -d1 output with this email...
>
> Do you think whether anything wrong with my vmcore ?
I'm not sure...
The dom0 "p2m_mfn" value required by the crash utility is
contained in the Xen XEN_ELFNOTE_CRASH_INFO note in the
vmcore header. That note contains this data structure,
as defined in "include/xen/elfcore.h" in the Xen hypervisor
source tree:
typedef struct {
unsigned long xen_major_version;
unsigned long xen_minor_version;
unsigned long xen_extra_version;
unsigned long xen_changeset;
unsigned long xen_compiler;
unsigned long xen_compile_date;
unsigned long xen_compile_time;
unsigned long tainted;
#ifdef CONFIG_X86
unsigned long xen_phys_start;
unsigned long dom0_pfn_to_mfn_frame_list_list;
#endif
} crash_xen_info_t;
When a dom0 crashes, it goes through machine_crash_shutdown()
in the hypervisor's "arch/x86/crash.c" file, where it gets a
pointer to the crash_xen_info structure, and then appends the
CONFIG_X86-only xen_phys_start and dom0_pfn_to_mfn_frame_list_list
fields:
void machine_crash_shutdown(void)
{
crash_xen_info_t *info;
local_irq_disable();
nmi_shootdown_cpus();
disable_IO_APIC();
hvm_disable();
info = kexec_crash_save_info();
info->xen_phys_start = xen_phys_start;
info->dom0_pfn_to_mfn_frame_list_list =
arch_get_pfn_to_mfn_frame_list_list(dom0);
}
And then the crash utility reads the dom0_pfn_to_mfn_frame_list_list
value, and stores it in the "p2m_mfn" field that I referenced in the
last email.
Now, looking at your crash -d1 output, here's the XEN_ELFNOTE_CRASH_INFO,
where it should have picked up the bf969 as the p2m_mfn value:
Elf64_Nhdr:
n_namesz: 4 ("Xen")
n_descsz: 80
n_type: 1000001 (XEN_ELFNOTE_CRASH_INFO)
00000003 00000000 00000004 00000000
d7beb409 00000000 d7bed168 00000000
d7bed138 00000000 d7beb3c5 00000000
d7beb3e2 00000000 00000000 00000000
d7a00000 00000000 000bf969 00000000
... [ snip ] ...
But it read it as a 0, as evidenced by the "p2m_mfn: 0" shown
below:
... [ snip ] ...
This GDB was configured as "i686-pc-linux-gnu"...
x86_xen_kdump_p2m_create: p2m_mfn: 0
... [ snip ] ...
In the meantime, I provisioned a RHEL5 32-bit x86 system with a 32-bit dom0,
and forced a crash. As expected, it created a 64-bit ELF vmcore, which
does *not* display the "mismatch" warning message like yours does. But more
importantly, the XEN_ELFNOTE_CRASH_INFO dump on my vmcore looks like this,
where the p2m_mfn is 2c199:
Elf64_Nhdr:
n_namesz: 4 ("Xen")
n_descsz: 40
n_type: 1000001 (XEN_ELFNOTE_CRASH_INFO)
00000003 00000001 0018e97f 0018e98a
00190120 0018e932 0018e94f 00000001
00000000 0002c199
Note that the fields in your vmcore are 64-bit values, while those above
in the RHEL5 are 32-bit values. That presumably is due to the fact that
you are running a 64-bit hypervisor? (whereas my RHEL5 the hypervisor is
a 32-bit) Are you *sure* that you are running a 32-bit hypervisor?
In any case, the p2m_mfn value in the vmcore header can be overridden
on the crash command line. What happens if you enter:
# crash vmlinux vmcore --p2m_mfn bf969
I'm guessing that you'll probably bump into yet another oddity, but it's
worth a shot...
Dave
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