"Sampathkumar, Kishore (STSD)" wrote:Hi Kishore,Hi,I have been working on back-porting kexec/kdump functionality from 2.6.13 vanilla kernel to RHEL4, Update 2 kernel (version 2.6.9-22).As part of that, when I try to invoke "crash" on a vmcore generated, I get the following error in "crash" tool:[root crash-4.0-2.23]# ./crash /boot/System.map-2.6.9-kdump-1 /usr/src/redhat/BUILD/kernel-2.6.9-kdump-1/linux- 2.6.9/vmlinux /root/vmcorecrash 4.0-2.23
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This GDB was configured as "x86_64-unknown-linux-gnu"...crash: read error: kernel virtual address: ffffffff813a8200 type: "xtime"[root crash-4.0-2.23]# [root crash-4.0-2.23]# I tried with both crash-4.0-2.15 as well as crash-4.0-2.23. Same result.- Should I be re-building crash as part of the back-port?- Is crash capable of handing vmcore's generated by kdump?- Can someone suggest how I can make progress to get crash to work for this?Thanks,- Kishore
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Hi Sampathkumar,First thing, presuming that the vmlinux file is associated with the vmcore
file, take the System-map argument out of the picture -- i.e, invoke the
session as:$ crash -d7 vmlinux vmcore
the -d7 will display a bunch of debug data.
What looks unusual is the ffffffff813a8200 address for "xtime". That
would seem to be too high -- except perhaps if the vmlinux you're working
against (or maybe the unnecessary System-map) is the kdump kernel loaded
at 16MB?If you do this, the output should show the exact same kernels:
$ strings vmcore | grep "Linux version"
$ strings vmlinux | grep "Linux version"
Dave
On a RHEL4 x86_64 kernel, "xtime" is typically an address about
3-4 MB from the beginning load address of the kernel, (i.e. add
about 3-4 MB to the base virtual address of ffffffff80000000),
whereas your example shows it at about 19MB (13a8200). Given
that
the dumpfile read of ffffffff813a8200 failed, it looks as if the
physical memory region containing that address was not dumped,
which AFAICT with other kdump dumpfiles I have on-hand, the
"64MB@16MB" (or whatever size at 16MB) that is reserved for
the kdump kernel would *not* be captured in the /proc/vmcore
file. So that kind of reinforces my suggestion that you are
perhaps using the wrong vmlinux (or System-map) associated with
the vmcore file.
Dave
