On Thu, Jul 31, 2014 at 02:03:31PM +0800, HuKeping wrote: > Add arm specific parts to kdump kernel documentation. > Hi Hu, So kexec on arm (32bit) now works? All the kernel pieces and kexec-tools pieces are upstream? (Sorry, I have not been able to keeptrack of arm development). > ---------------------------------------- > Signed-off-by: Hu Keping <hukeping at huawei.com> > --- > Documentation/kdump/kdump.txt | 25 ++++++++++++++++++++++--- > 1 file changed, 22 insertions(+), 3 deletions(-) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 88d5a86..5fc98d6 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, > -and s390x architectures. > +s390x and arm 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 > @@ -112,7 +112,7 @@ There are two possible methods of using Kdump. > 2) Or use the system kernel binary itself as dump-capture kernel and there is > no need to build a separate dump-capture kernel. This is possible > only with the architectures which support a relocatable kernel. As > - of today, i386, x86_64, ppc64 and ia64 architectures support relocatable > + of today, i386, x86_64, ppc64, ia64 and arm architectures support relocatable > kernel. So zImage is relocatable on arm? > > Building a relocatable kernel is advantageous from the point of view that > @@ -296,6 +296,12 @@ Boot into System Kernel > on the memory consumption of the kdump system. In general this is not > dependent on the memory size of the production system. > > + On arm, use "crashkernel=Y at X". Do you support other forms of crashkernel= parameter? Like crashkernel=X. A longer list of parameters is available in kernel-parameters.txt. > Note that the start address of the kernel > + will be aligned to 128MiB (0x08000000), x86 kernel is 2MB aligned. 128MB aligned seems to be huge. Where does that restriction come from. >so if the start address is not then > + any space blow the alignment point may be overwrited by the dump-caputre kernel, > + which means it is possible that the vmcore is not that precise as expected. What does above statement mean? I think it requires some work. And also some examples of what's a reasonable crashkernel=X at Y values for arm. > + > + > Load the Dump-capture Kernel > ============================ > > @@ -315,7 +321,8 @@ For ia64: > - Use vmlinux or vmlinuz.gz > For s390x: > - Use image or bzImage > - > +For arm: > + - Use zImage > > If you are using a uncompressed vmlinux image then use following command > to load dump-capture kernel. > @@ -331,6 +338,15 @@ to load dump-capture kernel. > --initrd=<initrd-for-dump-capture-kernel> \ > --append="root=<root-dev> <arch-specific-options>" > > +If you are using a compressed zImage, then use following command > +to load dump-capture kernel. > + > + kexec --type zImage -p <dump-capture-kernel-bzImage> \ > + --initrd=<initrd-for-dump-capture-kernel> \ > + --dtb=<dtb-for-dump-capture-kernel> \ > + --append="root=<root-dev> <arch-specific-options>" > + > + > Please note, that --args-linux does not need to be specified for ia64. > It is planned to make this a no-op on that architecture, but for now > it should be omitted > @@ -347,6 +363,9 @@ For ppc64: > For s390x: > "1 maxcpus=1 cgroup_disable=memory" > > +For arm: > + "1 maxcpus=1 reset_devices" > + nr_cpus=1 does not work on arm? We prefer that over maxcpus=1. Thanks Vivek
