On 07/11/2013 07:21 PM, Michael Ellerman wrote: > On Thu, Jul 11, 2013 at 03:22:49PM -0600, Chris Friesen wrote: >> On 07/11/2013 02:55 PM, Chris Friesen wrote: >>> Hi, >>> >>> I'm running 2.6.34 with kexec 2.0.1 on a Freescale p5020-based system >>> with 8GB of memory. (It's an embedded system and I can't do much >>> about the fact that it's using older software.) >> >> I should probably clarify this...I may be able to update kexec, I >> can't update the kernel but I can backport more recent code if >> necessary. >> >> Looking at the version of kexec that I have, it seems like where x86 >> uses "memmap=" to specify the memory map usable by the capture >> kernel, powerpc does something different. > > From memory, it's been years, on powerpc we add properties to the memory > nodes in the device tree that specify which memory is usable. The > properties are called "linux,usable-memory", and in modern kernels they > are read in early_init_dt_scan_memory(). 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? Chris
