Vivek, can you help to give some comments about the locate hole isssue in kexec_file? On 04/28/17 at 09:51am, AKASHI Takahiro wrote: > Thiago, > > Thank you for the comment. > > On Thu, Apr 27, 2017 at 07:00:04PM -0300, Thiago Jung Bauermann wrote: > > Hello, > > > > Am Mittwoch, 26. April 2017, 17:22:09 BRT schrieb AKASHI Takahiro: > > > The current kexec_locate_mem_hole(kbuf.top_down == 1) stops searching at > > > the first memory region that has enough space for requested size even if > > > some of higher regions may also have. > > > > kexec_locate_mem_hole expects arch_kexec_walk_mem to walk memory from top to > > bottom if top_down is true. That is what powerpc's version does. > > Ah, I haven't noticed that, but x86 doesn't have arch_kexec_walk_mem and > how can it work for x86? > > > Isn't it possible to walk resources from top to bottom? > > Yes, it will be, but it seems to me that such a behavior is not intuitive > and even confusing if it doesn't come with explicit explanation. Thing need to make clear is why do we need the change, it might be a problem for crashkernel=xM,low since that is for softiotlb in case crashkernel=xM,high being used, otherwise seems current code is fine. Need seeking for old memory from Vivek to confirm. > > > > This behavior is not consistent with locate_hole(hole_end == -1) function > > > of kexec-tools. > > > > > > This patch fixes the bug, going though all the memory regions anyway. > > > > This patch would break powerpc, because at the end of the memory walk kbuf > > would have the lowest memory hole. > > > > If it's not possible to walk resources in reverse order, then this patch needs > > to change powerpc to always walk memory from bottom to top. > > So I would like to hear from x86 guys. > > Thanks > -Takahiro AKASHI > > > -- > > Thiago Jung Bauermann > > IBM Linux Technology Center > >
