On Thu, 4 Sep 2025 09:19:21 +0200, Ard Biesheuvel <[email protected]> wrote: > On Sat, 23 Aug 2025 at 23:47, Ard Biesheuvel <[email protected]> wrote: > > > > (cc Ilias) > > > > Note to akpm: please drop this series for now. > > > > On Fri, 22 Aug 2025 at 04:00, Evangelos Petrongonas <[email protected]> > > wrote: > > > > > > When KHO (Kexec HandOver) is enabled, it sets up scratch memory regions > > > early during device tree scanning. After kexec, the new kernel > > > exclusively uses this region for memory allocations during boot up to > > > the initialization of the page allocator > > > > > > However, when booting with EFI, EFI's reserve_regions() uses > > > memblock_remove(0, PHYS_ADDR_MAX) to clear all memory regions before > > > rebuilding them from EFI data. This destroys KHO scratch regions and > > > their flags, thus causing a kernel panic, as there are no scratch > > > memory regions. > > > > > > Instead of wholesale removal, iterate through memory regions and only > > > remove non-KHO ones. This preserves KHO scratch regions, which are > > > good known memory, while still allowing EFI to rebuild its memory map. > > > > > > Acked-by: Mike Rapoport (Microsoft) <[email protected]> > > > Signed-off-by: Evangelos Petrongonas <[email protected]> > > > --- > > > Changes in v3: > > > - Improve the code comments, by stating that the scratch regions > > > are > > > good known memory > > > > > > Changes in v2: > > > - Replace the for loop with for_each_mem_region > > > - Fix comment indentation > > > - Amend commit message to specify that scratch regions > > > are known good regions > > > > > > drivers/firmware/efi/efi-init.c | 29 +++++++++++++++++++++++++---- > > > 1 file changed, 25 insertions(+), 4 deletions(-) > > > > > > > I'd rather drop the memblock_remove() entirely if possible. Could we > > get some insight into whether memblocks are generally already > > populated at this point during the boot? > > > > > > Ping?
Hey Ard I was AFK travelling. I am back now and will get to it. PS: Keen to meet you later today in the KVM Forum. Kind Regards, Evangelos Amazon Web Services Development Center Germany GmbH Tamara-Danz-Str. 13 10243 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597
