Manish, On Tue, Oct 04, 2016 at 06:53:28PM +0530, Manish Jaggi wrote: > > On 10/04/2016 04:23 PM, James Morse wrote: > > Hi Manish, > > > > On 04/10/16 11:05, Manish Jaggi wrote: > >> On 10/04/2016 03:16 PM, James Morse wrote: > >>> 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: > >>>>>> 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. > > > > Not with v26 of this series. What should it do with the 62G of memory that was > > removed by booting with 'mem=2G'? It isn't part of the crashkernel reserved > > area, and it isn't part of the vmcore described in elfcorehdr either... > > > > > >> 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? > > > > Yes, on juno-r1 passing 'mem=2G' to both the first and second kernel causes only > > the first 2G of memory to be used with this pattern: > > first kernel: [1G used for linux] [1G reserved for Crash kernel] [6G memory > > hidden] > > kdump kernel: [1G vmcore] [1G used for linux] [6G memory hidden] > > > > > Oh, ok! > I was giving mem=1G to crashkernel to test. with mem=2G it works. I didn't know that you specified "mem=1G" in our local discussions ... > >>>>>> 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. > > > > Ah, you want to run /usr/bin/crash with the kdump boot of linux. You still need > > to tell it where to find the memory image: "crash /path/to/vmlinux /proc/vmcore" > > should do the trick. > > > We should fix the documentation of kdump them. > Since it is not supported, it should be removed. Remove what? And can you please double-check if you still have any problem on a live system or with a saved core file? (except for "mem=" stuff) -Takahiro AKASHI > > Thanks, > > > > James > >
