On 10/04/2016 03:16 PM, James Morse wrote: > Hi Manish, > > On 03/10/16 13:41, Manish Jaggi wrote: >> On 10/03/2016 04:34 PM, AKASHI Takahiro wrote: >>> On Mon, Oct 03, 2016 at 01:24:34PM +0530, Manish Jaggi wrote: >>>> With the v26 kdump and v3 kexec-tools and top of tree crash.git, below are the tests done >>>> Attached is a patch in crash.git (symbols.c) to make crash utility work on my setup. >>>> Can you please have a look and provide your comments. >>>> >>>> To generate a panic, i have a kernel module which on init calls panic. > > ... modules ... I haven't tested that. I bet it causes some problems! > We probably need to include module_alloc_base as an elf note in the vmcore file... > > >>>> First kernel is booted with mem=2G crashkernel=1G command line option. >>>> While the system has 64G memory. > >>> Are you saying that "mem=..." doesn't have any effect? >> What I am saying it that If the first kernel is booted using mem= option and crashkernel= option >> the memory for second kernel has to be withing the crashkernel size. >> As per /proc/iomem System RAM the information is correct, but the /proc/meminfo is showing total memory >> much more than the first kernel had in first place. > > So your second crashkernel has 63G of memory? Unless you provide the same 'mem=' > to the kdump kernel, this is the expected behaviour. The > DT:/reserved-memory/crash_dump describes the memory not to use. > > On your first boot with 'mem=2G' memblock_mem_limit_remove_map() called from > arm64_memblock_init() removed the top 62G of memory. Neither the first kernel > nor kexec-tools know about the top 62G. > When you run kexec-tools, it describes what it sees in /proc/iomem in the > DT:/reserved-memory/crash_dump, which is just the remaining 1G of memory. > > When we crash and reboot, the crash kernel discovers all 64G of memory from the > EFI memory map. So the iomem and meminfo should be same or different for the second kernel? Also i assumed that crashkernel=1G should restrict the second kernels to 1G. This is my understanding from the description. It should not require a second mem= option > kexec-tools described the 1G of memory that the first kernel was using in the > DT:/reserved-memory/crash_dump node, so early_init_fdt_scan_reserved_mem() > reserves the 1G of memory the first kernel used. This leaves us with 63G of memory. > > This may change with the next version of kdump if it switches back to using > DT:/chosen/linux,usable-memory-range. > If you need v26 to avoid the top 62G of memory, you need to provide the same > 'mem=' to the first and second kernel. If I provide for second kernel, I dont see any prints after Bye. Have you tired this anytime? > > >>>> 1.2 Live crash dump fails with error > > ... do we expect this to work? I don't think it has anything to do with this > series... > Why it should not? I saved the vmcore file while in second kernel. Since crash without vmcore file didnt run, Tried with vmcore file and it worked. Its just that if you want to boot a second kernel with read only file system without network live crash dump analysis is handy. > > Thanks, > > James >
