Hi Xunlei, On Wednesday 22 March 2017 03:04 PM, Xunlei Pang wrote: > On 03/22/2017 at 12:30 PM, Dave Young wrote: >> On 03/21/17 at 10:18pm, Eric W. Biederman wrote: >>> Dave Young <dyoung at redhat.com> writes: >>> >>>> On 03/20/17 at 10:33pm, Eric W. Biederman wrote: >>>>> Xunlei Pang <xlpang at redhat.com> writes: >>>>> >>>>>> As Eric said, >>>>>> "what we need to do is move the variable vmcoreinfo_note out >>>>>> of the kernel's .bss section. And modify the code to regenerate >>>>>> and keep this information in something like the control page. >>>>>> >>>>>> Definitely something like this needs a page all to itself, and ideally >>>>>> far away from any other kernel data structures. I clearly was not >>>>>> watching closely the data someone decided to keep this silly thing >>>>>> in the kernel's .bss section." >>>>>> >>>>>> This patch allocates extra pages for these vmcoreinfo_XXX variables, >>>>>> one advantage is that it enhances some safety of vmcoreinfo, because >>>>>> vmcoreinfo now is kept far away from other kernel data structures. >>>>> Can you preceed this patch with a patch that removes CRASHTIME from >>>>> vmcoreinfo? If someone actually cares we can add a separate note that holds >>>>> a 64bit crashtime in the per cpu notes. >>>> I think makedumpfile is using it, but I also vote to remove the >>>> CRASHTIME. It is better not to do this while crashing and a makedumpfile >>>> userspace patch is needed to drop the use of it. >>>> > By moving the CRASHTIME info to the cpu note of crashed cpu may be a good > way. In kdump kernel, notes of vmcore elfhdr will be merged into one big note > section, I don't know how makedumpfile or crash handle the big note section? > If they process the note in some order, breakage will definitely happen... > > There is also a fadump may be affected. > Would like to keep a tab of such change as fadump builds cpu notes differently and such change may have an impact on it considering it depends on the same tools - crash, makedumpfile.. Thanks Hari
