[PATCH 3/3] powerpc/ppc64/kdump: better flag for running relocatable
miltonm at bga.com
Sat Nov 8 00:52:31 EST 2008
On Oct 22, 2008, at 10:43 PM, Paul Mackerras wrote:
> Paul Mackerras writes:
>> Milton Miller writes:
>>> Move the flag to 0x5c, 1 word before the secondary cpu entry point at
>>> 0x60. Use the copy at address 0 not the one in the base kernel
>>> image to
>>> make it easier on kexec-tools.
>> Why is it easier on kexec-tools? Doesn't kexec-tools know where it
>> put the kernel?
The archictecture code calls cross-platform code to identify what is
loaded. It isn't specified if this is a shared mmap or a read into
>> I'd much rather keep the flag inside the kdump kernel image, rather
>> than having kexec/kdump start using random fixed locations outside the
>> new kernel image.
> In fact the cliching argument is that when the kernel is loaded by OF
> or yaboot, we have no way to tell what will be at location 0x5c,
> whereas we know that the word at offset 0x5c in the kernel image will
> have been initialized to 0. So we had better put the flag inside the
> kernel image.
Well, prom_init will copy the 256 bytes to 0 before the code checks
However, there is an arguement for using the same code from an epapr
or book-e relocatable, and that would need it at 0. And today
the kexec tool does not do a shared mmap. Since the change has
been made, I will make a new patch for kexec-tools.
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