kexec does not work for kernel version with patch level >= 256

[Patrick Sung]

Hello all,

I am using the 4.9 long term kernel which is currently at 4.9.262.
When using this kernel with kexec-tools it prints out this error

  Unsupported utsname.release: 4.9.262
  Cannot load <kdump images path>

A quick search in the code shows that kexec/kernel_version.c doing this check:

  if (major >= 256 || minor >= 256 || patch >= 256) {

and also in kexec/kexec.h
  #define KERNEL_VERSION(major, minor, patch) \
    (((major) << 16) | ((minor) << 8) | patch)

which explains the reason for the range check in kernel_version.c

Increasing the number of bits allowed in "patch" seems to fix the issue.

Thanks,
Patrick