kexec/kdump produces incomplete dump files with kernel 2.6.20 + CONFIG_HIGHMEM64G

Dave Anderson anderson at
Fri Oct 17 12:19:44 EDT 2008

> Do you use the same kernel as the running kernel as capture kernel?
> Regards,
> Bernhard

If I may butt in here -- Kevin's capture kernel is "standard" 3GB/1GB
kernel, whereas his primary kernel is his 1GB/3GB kernel.

Also to clarify, since vmalloc memory is biased to be allocated
from highmem, in his 1GB/3GB kernel it comes from physical memory
above his kernel's 3GB "unity-mappable" range.  And his system happens
to have a 1GB chunk of physical memory from 4GB to 5GB physical, so
his vmalloc memory comes from the physical address 0x100000000 and
above.  Data is read OK on the live system from that region of memory,
but when read from the same physical address on the dumpfile, it always
returns zeroes.


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