Messages in this thread | | | Date | Thu, 14 Aug 2008 03:36:35 -0700 | From | "Yinghai Lu" <> | Subject | Re: HPET regression in 2.6.26 versus 2.6.25 -- revert for 2.6.26-rc1 failed |
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On Thu, Aug 14, 2008 at 3:04 AM, Bill Fink <billfink@mindspring.com> wrote: > 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.
why oops ? if not valid crash kernel size etc is input, crashk_res_ptr will be null
> if (crashk_res_ptr) { > res_kernel[num_res] = crashk_res_ptr; > num_res++; > }
it that is not appended to res_kernel...
YH
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