After crashkernel=,high support was added, our QE engineer surprisingly found the reserved crashkernel high region could cross the high low memory boundary. E.g on system with 4G as boundary, the crashkernel high region is [4G-64M, 4G+448M]. After investigation, I noticed on arm64, the area near 4G is contiguous. Not like x86, its firmware occupies the cpu address space below 4G. When memblock searches for available memory region top down, it could find a region across 4G boundary. Finally, we actually got two memory regions in low memory. This complicates the crashkernel=,high behaviour, people will be confused by this. In this patchset, simpliyfy the behaviour of crashkernel=,high. When trying to reserve memory region for crashkernel high, we only search for the region in high memory, e.g above 4G. If failed, try searching in low memory. This makes sure the crashkernel high memory limited in high memory, confusion is removed. In patch 2, I add code comment above several crashkernel reservation case to ease code reading. I put them in a separate patch 2 because I want the code change in patch 1 to be straightforward and simpler for reviewing. Please help review and check if this is helpful and worth. Baoquan He (2): arm64: kdump: simplify the reservation behaviour of crashkernel=,high arm64/kdump: add code comments for crashkernel reservation cases arch/arm64/mm/init.c | 43 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-) -- 2.34.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
