[Crash-utility] Linux Banner string missing.

[Dave Anderson]

----- "Feng LI" <funglee at gmail.com> wrote:

> Hey Dave and list,
> 
> 
> I am the guy who is try to open the 64 bit vmcore dump with 64 bit xen
> kernel and 32 bit dom0 kernel.
> 
> 
> Finally, I have received the dom0 kernel with symbols, and I tried to
> open the vmcore with crash (I patched with your "special patch").
> 
> 
> But I have a new problem, the crash utility exits with an error "could
> not read linux_banner string"
> 
> 
> <readmem: c034c000, KVADDR, "accessible check", 4, (ROE|Q), ffff82e4>
> addr: c034c000 paddr: 34c000 cnt: 4
> <readmem: c034c000, KVADDR, "readstring characters", 1499, (ROE|Q),
> ffff72d0>
> addr: c034c000 paddr: 34c000 cnt: 1499
> WARNING: cannot read linux_banner string
> linux_banner:
> 
> 
> crash32: boot/System.map-2.6.27.42-0.1.1.xs5.6.0.44.111158xen and
> vmcore-2010-09-15-19-29-03 do not match!
> 
> Have you seen these error message before ? and Thanks for any help and
> suggestion.
> 
> 
> yours
> Kevin F LI
> 
> 
> ps.
> I attached the log file generated with "-d 31" option. 

Looking at the attached log file, things are regressing even further
than what was shown in your original reports.  This time the vmcore
is not even being recognized as a Xen-generated core dump:

       ...
              page_size: 0
           switch_stack: 0
         xen_kdump_data: (unused)   <== this time
       num_prstatus_notes: 0
               vmcoreinfo: 0
          size_vmcoreinfo: 0
       nt_prstatus_percpu: 
       ...

In your older post, it at least showed some xen_kdump_data:

        ...
              page_size: 0
           switch_stack: 0
         xen_kdump_data:  
                    flags: 4 (KDUMP_MFN_LIST)
                  p2m_mfn: 0
                      cr3: 0
            last_mfn_read: ffffffff
            last_pmd_read: ffffffff
                     page: 0
                 accesses: 0
               cache_hits: 0 
               p2m_frames: 0
           xen_phys_start: 7db00000
        xen_major_version: 3
        xen_minor_version: 0
       p2m_mfn_frame_list: 0
       num_prstatus_notes: 4
               vmcoreinfo: 0
          size_vmcoreinfo: 0
       nt_prstatus_percpu: 
        084c8e10 084c9004 084c9198 084c932c 
       ...

That may be due to the use of a System.map file, which forces
the crash utility to take some short-cuts during initialization.
Or again, it could be a side issue of the lack of crash utility
support for 32-bit vmcores taken from 64-bit Xen hypervisors.

But since you've apparently got the debuginfo-full dom0 vmlinux 
file, then there's not need to use the System.map file.   What
happens when you just run: "crash -d1 vmlinux vmcore"?

Dave