On Thu, Jan 13, 2022 at 07:33:11PM +0200, Mike Rapoport wrote: > On Tue, Jan 11, 2022 at 08:44:41PM +0000, Frank van der Linden wrote: > > On Tue, Jan 11, 2022 at 12:31:58PM +0200, Mike Rapoport wrote: > > > > --- a/include/linux/memblock.h > > > > +++ b/include/linux/memblock.h > > > > @@ -481,6 +481,8 @@ phys_addr_t memblock_reserved_size(void); > > > > phys_addr_t memblock_start_of_DRAM(void); > > > > phys_addr_t memblock_end_of_DRAM(void); > > > > void memblock_enforce_memory_limit(phys_addr_t memory_limit); > > > > +void memblock_set_usable_range(phys_addr_t base, phys_addr_t size); > > > > +void memblock_enforce_usable_range(void); > > > > void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size); > > > > void memblock_mem_limit_remove_map(phys_addr_t limit); > > > > > > We already have 3 very similar interfaces that deal with memory capping. > > > Now you suggest to add fourth that will "generically" solve a single use > > > case of DT, EFI and kdump interaction on arm64. > > > > > > Looks like a workaround for a fundamental issue of incompatibility between > > > DT and EFI wrt memory registration. > > > > Yep, I figured this would be the main argument against this - arm64 > > already added several other more-or-less special cased interfaces over > > time. > > > > I'm more than happy to solve this in a different way. > > > > What would you suggest: > > > > 1) Try to merge the similar interfaces in to one. > > 2) Just deal with it at a lower (arm64) level? > > 3) Some other way? > > We've discussed this with Ard on IRC, and our conclusion was that on arm64 > kdump kernel should have memblock.memory exactly the same as the normal > kernel. Then, the memory outside usable-memory-range should be reserved so > that kdump kernel won't step over it. > > With that, simple (untested) patch below could be what we need: > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index bdca35284ceb..371418dffaf1 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -1275,7 +1275,8 @@ void __init early_init_dt_scan_nodes(void) > of_scan_flat_dt(early_init_dt_scan_memory, NULL); > > /* Handle linux,usable-memory-range property */ > - memblock_cap_memory_range(cap_mem_addr, cap_mem_size); > + memblock_reserve(0, cap_mem_addr); > + memblock_reserve(cap_mem_addr + cap_mem_size, PHYS_ADDR_MAX); > } > > bool __init early_init_dt_scan(void *params) Ok, tested this on 5.17-rc, and it's working OK there. Main kernel has 32G, crash kernel gets 512M: Main kernel: [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] [ 0.000000] DMA32 empty [ 0.000000] Normal [mem 0x0000000100000000-0x0000000b96ffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000040000000-0x00000000786effff] [ 0.000000] node 0: [mem 0x00000000786f0000-0x000000007872ffff] [ 0.000000] node 0: [mem 0x0000000078730000-0x000000007bbfffff] [ 0.000000] node 0: [mem 0x000000007bc00000-0x000000007bfdffff] [ 0.000000] node 0: [mem 0x000000007bfe0000-0x000000007fffffff] [ 0.000000] node 0: [mem 0x0000000400000000-0x0000000b96ffffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x0000000b96ffffff] [ 0.000000] On node 0, zone Normal: 4096 pages in unavailable ranges [ 0.000000] cma: Reserved 64 MiB at 0x000000007c000000 [ 0.000000] crashkernel reserved: 0x0000000054400000 - 0x0000000074400000 (512 MB) Crash kernel: [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000054400000-0x000000007bfdffff] [ 0.000000] DMA32 empty [ 0.000000] Normal empty [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000054400000-0x00000000743fffff] [ 0.000000] node 0: [mem 0x00000000786f0000-0x000000007872ffff] [ 0.000000] node 0: [mem 0x000000007bc00000-0x000000007bfdffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000054400000-0x000000007bfdffff] [ 0.000000] On node 0, zone DMA: 17408 pages in unavailable ranges [ 0.000000] On node 0, zone DMA: 17136 pages in unavailable ranges [ 0.000000] On node 0, zone DMA: 13520 pages in unavailable ranges [ 0.000000] On node 0, zone DMA: 16416 pages in unavailable ranges Not sure why I had trouble with the same on 5.15, I'll have to look at that again. But this seems fine for 5.16+ Thanks, - Frank
