Dave, On 05/11/2015 04:47 PM, Dave Young wrote: > On 05/08/15 at 08:19pm, Dave Young wrote: >> Hi, >> >> On 04/24/15 at 04:53pm, AKASHI Takahiro wrote: >>> Please read the following commits for arm64-specific constraints: >>> arm64: kdump: reserve memory for crash dump kernel >>> arm64: kdump: do not go into EL2 before starting a crash dump kernel >>> >>> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org> >>> --- >>> Documentation/kdump/kdump.txt | 31 ++++++++++++++++++++++++++++++- >>> arch/arm64/Kconfig | 12 ++++++++++++ >>> 2 files changed, 42 insertions(+), 1 deletion(-) >>> >>> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >>> index bc4bd5a..f9cf6f5 100644 >>> --- a/Documentation/kdump/kdump.txt >>> +++ b/Documentation/kdump/kdump.txt >>> @@ -18,7 +18,7 @@ memory image to a dump file on the local disk, or across the network to >>> a remote system. >>> >>> Kdump and kexec are currently supported on the x86, x86_64, ppc64, ia64, >>> -s390x and arm architectures. >>> +s390x, arm and arm64 architectures. >>> >>> When the system kernel boots, it reserves a small section of memory for >>> the dump-capture kernel. This ensures that ongoing Direct Memory Access >>> @@ -249,6 +249,29 @@ Dump-capture kernel config options (Arch Dependent, arm) >>> >>> AUTO_ZRELADDR=y >>> >>> +Dump-capture kernel config options (Arch Dependent, arm64) >>> +---------------------------------------------------------- >>> + >>> +1) Disable symmetric multi-processing support under "Processor type and >>> + features": >>> + >>> + CONFIG_SMP=n >>> + >>> + (If CONFIG_SMP=y, then specify maxcpus=1 on the kernel command line >>> + when loading the dump-capture kernel, see section "Load the Dump-capture >>> + Kernel".) >>> + >>> +2) Under uefi, the maximum memory size on the dump-capture kernel must be >>> + limited by specifying: >>> + >>> + mem=X[MG] >>> + >>> + where X should be less than or equal to the size in "crashkernel=" >>> + boot parameter. Kexec-tools will automatically add this. >> >> I noticed you are passing mem=X in kexec-tools, Pratyush found a problem >> that vmcore is corrupted because kdump kernel is using the crash notes memory. >> >> How does kdump kernel know the system ram range especially the mem_start? >> Only with the size from mem=? parammeter? >> >> In X86 because it use E820 so kexec-tools can pass the memory range to kdump >> kernel even for UEFI booting. But in arm64 may need find other way to >> communicate with 2nd kernel like memmap=exactmap in X86.. > > Discussed with Pratyush in irc, he mentioned that start address is get from > kernel->entry which was passed by kexec-tools. > > So sorry for the noise, it will works fine with the UEFI mem= limitation > fix from Mark Salter No, not at all. As you know, in another thread (with Mark), we're discussing this. If we conclude that we should go for "memmap=" approach, I will update my patch. Thanks, -Takahiro AKASHI >> >>> + >>> +3) Currently, kvm will not be initialized on the dump-capture kernel even >>> + if it is configured. >>> + >>> Extended crashkernel syntax >>> =========================== >>> >>> @@ -312,6 +335,7 @@ Boot into System Kernel >>> any space below the alignment point may be overwritten by the dump-capture kernel, >>> which means it is possible that the vmcore is not that precise as expected. >>> >>> + On arm64, use "crashkernel=Y at X". >>> >>> Load the Dump-capture Kernel >>> ============================ >>> @@ -334,6 +358,8 @@ For s390x: >>> - Use image or bzImage >>> For arm: >>> - Use zImage >>> +For arm64: >>> + - Use vmlinux >>> >>> If you are using a uncompressed vmlinux image then use following command >>> to load dump-capture kernel. >>> @@ -377,6 +403,9 @@ For s390x: >>> For arm: >>> "1 maxcpus=1 reset_devices" >>> >>> +For arm64: >>> + "1 maxcpus=1 mem=X[MG] reset_devices" >>> + >>> Notes on loading the dump-capture kernel: >>> >>> * By default, the ELF headers are stored in ELF64 format to support >>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >>> index 5716edf..8e2f545 100644 >>> --- a/arch/arm64/Kconfig >>> +++ b/arch/arm64/Kconfig >>> @@ -562,6 +562,18 @@ config KEXEC >>> but it is independent of the system firmware. And like a reboot >>> you can start any kernel with it, not just Linux. >>> >>> +config CRASH_DUMP >>> + bool "Build kdump crash kernel" >>> + help >>> + Generate crash dump after being started by kexec. This should >>> + be normally only set in special crash dump kernels which are >>> + loaded in the main kernel with kexec-tools into a specially >>> + reserved region and then later executed after a crash by >>> + kdump/kexec. The crash dump kernel must be compiled to a >>> + memory address not used by the main kernel. >>> + >>> + For more details see Documentation/kdump/kdump.txt >>> + >>> config XEN_DOM0 >>> def_bool y >>> depends on XEN >>> -- >>> 1.7.9.5 >>> >>> >>> _______________________________________________ >>> kexec mailing list >>> kexec at lists.infradead.org >>> http://lists.infradead.org/mailman/listinfo/kexec >>> >>> >> >> _______________________________________________ >> kexec mailing list >> kexec at lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec >> >>
