Messages in this thread | | | Date | Thu, 14 Aug 2008 06:04:33 -0400 | From | Bill Fink <> | Subject | Re: HPET regression in 2.6.26 versus 2.6.25 -- revert for 2.6.26-rc1 failed |
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Hi David,
On Wed, 13 Aug 2008, David Witbrodt wrote:
> [Yinghai, please note that I did not request a patch to revert the > problem commit. I was merely experimenting -- on my own time, so > you folks would not have to bother -- to see if I could make it > work. I should have made that more clear! Having said that, I am > glad to test changes of any kind on my machine: reverts, code for > debugging or info, experiments, etc.]
I'm not sure Yinghai's revert patch is completely equivalent to a revert of the original problematic commit, by a side-by-side comparison of the original commit with his recent revert patch, but then I don't really know that code at all.
In the original code there was a section (in e820_reserve_resources()):
#ifdef CONFIG_KEXEC if (crashk_res.start != crashk_res.end) request_resource(res, &crashk_res); #endif
If you don't have CONFIG_KEXEC defined in your .config, which is probably the case, then you would never request a crashk_res resource. But in the code after the original commit, it unconditionally calls (in reserve_crashkernel()):
crashk_res.start = crash_base; crashk_res.end = crash_base + crash_size - 1; insert_resource(&iomem_resource, &crashk_res);
And after Yinghai's revert patch it still does (in reserve_crashkernel()):
crashk_res.start = crash_base; crashk_res.end = crash_base + crash_size - 1; crashk_res_ptr = &crashk_res;
and (in setup_arch()):
num_res = 3; if (crashk_res_ptr) { res_kernel[num_res] = crashk_res_ptr; num_res++; } e820_reserve_resources(res_kernel, num_res);
then (in e820_reserve_resources()):
for (j = 0; j < nr_res_k; j++) { if (!res_kernel[j]) continue; request_resource(res, res_kernel[j]); }
which for j == 3 is:
request_resource(res, &crashk_res);
Now it would appear that the new:
insert_resource(&iomem_resource, &crashk_res);
or new:
request_resource(res, &crashk_res);
should be noops. But if for any reason crash_size is not zero, then there could be a difference. I have no idea if this is at all significant, but I thought I'd point it out just in case.
-Bill
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