On 07/13/2013 01:30:50 AM, Chris Friesen wrote: > On 07/12/2013 04:59 PM, Chris Friesen wrote: >> On 07/12/2013 03:08 PM, Chris Friesen wrote: >> >>> I turned on the instrumentation in early_init_dt_scan_memory() and >>> got >>> the following when jumping to the capture kernel: >>> >>> memory scan node memory, reg size 16, data: 0 0 2 0, >>> - 0 , 200000000 >>> >>> That 0x200000000 matches the fact that I'm seeing 8GB of memory >>> available in the recovery kernel. >>> >>> If I boot the original kernel with "crashkernel=224M at 32M", should I >>> expect that only 224MB is marked as "linux,usable-memory" in the >>> recovery kernel? >> >> I started looking at the kexec side of things, and I noticed >> something a >> bit odd. In most places dealing with the device tree in kexec it >> accepts >> either "memory" or "memory@" for the memory node name. In >> add_usable_mem_property() in arch/ppc64/fs2dt.c it seems to only >> accept >> "memory@". >> >> Is this expected behaviour? It seems to be the same in current git >> versions of kexec-tools. >> >> On my system I see "/proc/device-tree/memory". >> >> If I modify add_usable_mem_property() to also accept "/memory" then >> my >> recovery kernel boots up with >> >> physicalMemorySize = 0x10000000 >> >> which is 256MB (which is still a bit odd since I specified 224MB for >> the >> crashkernel). >> >> However, it then hits the BUG() call at the end of mark_bootmem() in >> mm/bootmem.c. > > One final thing and I'll stop replying to myself. :) > > It looks like the problem is that some board-specific freescale code > was calling lmb_reserve() with a base address in the 4GB range. It > seems odd that lmb_reserve() didn't throw some kind of error when the > recovery kernel was supposed to be limited to 224MB. > > Rather than try and fix the bug, I turned off the (unneeded) config > options related to the above lmb_reserve() calls and was able to > successfully access the information I needed via /dev/oldmem. > > The upshot is that there seems to be a number of things that could be > improved: > > 1) kexec should accept "/memory" and not just "/memory@" > 2) lmb_reserve() should really respect the crashkernel memory limit > 3) the freescale stuff really shouldn't assume it can map things > wherever it feels like What "board-specific freescale code" are you referring to? -Scott
