On Fri, Jan 15, 2016 at 07:18:38PM +0000, Geoff Levand wrote: > From: AKASHI Takahiro <takahiro.akashi at linaro.org> > > This patch adds arch specific descriptions about kdump usage on arm64 > to kdump.txt. > > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org> > --- > Documentation/kdump/kdump.txt | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index bc4bd5a..36cf978 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 +249,20 @@ Dump-capture kernel config options (Arch Dependent, arm) > > AUTO_ZRELADDR=y > > +Dump-capture kernel config options (Arch Dependent, arm64) > +---------------------------------------------------------- > + > +1) 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. This is extremely fragile, and will trivially fail when the kernel can be loaded anywhere (see [1]). We must explicitly describe the set of regions the crash kernel may use (i.e. we need base and size). NAK in the absence of that. Thanks, Mark. > + > +2) Currently, kvm will not be enabled on the dump-capture kernel even > + if it is configured. > + > Extended crashkernel syntax > =========================== > > @@ -312,6 +326,8 @@ 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[@X]". Note that the start address of > + the kernel, X if explicitly specified, must be aligned to 2MiB (0x200000). > > Load the Dump-capture Kernel > ============================ > @@ -334,6 +350,8 @@ For s390x: > - Use image or bzImage > For arm: > - Use zImage > +For arm64: > + - Use vmlinux or Image > > If you are using a uncompressed vmlinux image then use following command > to load dump-capture kernel. > @@ -377,6 +395,9 @@ For s390x: > For arm: > "1 maxcpus=1 reset_devices" > > +For arm64: > + "1 mem=X[MG] maxcpus=1 reset_devices" > + > Notes on loading the dump-capture kernel: > > * By default, the ELF headers are stored in ELF64 format to support > -- > 2.5.0 > > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/398527.html
