Re: [Fastboot] [PATCH] Kdump documentation update for 2.6.20: ia64

Jay Lan
2007-01-12T19:46:39Z

Horms wrote:
> Hi,
>
> this patch fills in the portions for ia64 kexec.
>
> I'm actually not sure what options are required for the dump-capture
> kernel, but "init 1 irqpoll maxcpus=1" has been working fine for me.
> Or more to the point, I'm not sure if irqpoll is needed or not.
>
> This patch requires the documentation patch update that Vivek Goyal has
> been circulating, and I believe is currently in mm. Feel free to fold it
> into that change if it makes things easier for anyone.
>
> Take II
>
> Nanhai,
>
> I have noted that vmlinux.gz may also be used. And added a note about the
> kernel being able to automatically place the crashkernel region.
> Furthermore, I added a note that if manually specified, the region should
> be 64Mb aligned to avoid wastage. I notice that the auto placement code
> uses 64Mb. But is this strictly neccessary for all page sizes?
>
> Signed-off-by: Simon Horman <horms@verge.net.au>
>
> Index: linux-2.6/Documentation/kdump/kdump.txt
> =================================> --- linux-2.6.orig/Documentation/kdump/kdump.txt 2007-01-12 17:45:19.000000000 +0900
> +++ linux-2.6/Documentation/kdump/kdump.txt 2007-01-12 17:59:42.000000000 +0900
> @@ -17,7 +17,7 @@
> 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 and IA64
> +Kdump and kexec are currently supported on the x86, x86_64, ppc64 and ia64
> architectures.
>
> When the system kernel boots, it reserves a small section of memory for
> @@ -229,7 +229,23 @@
>
> Dump-capture kernel config options (Arch Dependent, ia64)
> ----------------------------------------------------------
> -(To be filled)
> +
> +- No specific options are required to create a dump-capture kernel
> + for ia64, other than those specified in the arch idependent section
> + above. This means that it is possible to use the system kernel
> + as a dump-capture kernel if desired.
> +
> + The crashkernel region can be automatically placed by the system
> + kernel at run time. This is done by specifying the base address as 0,
> + or omitting it all together.

In my testing, i found the base address was ignored. Whatever value
specified was fine. Not necessary to be 0. But i guess it is fine to
give people a guideline telling them to specify 0.

Cheers,
- jay

> +
> + crashkernel%6M@0
> + or
> + crashkernel%6M
> +
> + If the start address is specified, not that the start address of the
> + kernel will be alligned to 64Mb, so any if the start address is not then
> + any space below the alignment point will be wasted.
>
>
> Boot into System Kernel
> @@ -248,6 +264,10 @@
>
> On ppc64, use "crashkernel\x128M@32M".
>
> + On ia64, 256M@256M is a generous value that typically works.
> + The region may be automatically placed on ia64, see the
> + dump-capture kernel config option notes above.
> +
> Load the Dump-capture Kernel
> ==============
>
> @@ -266,7 +286,8 @@
> For ppc64:
> - Use vmlinux
> For ia64:
> - (To be filled)
> + - Use vmlinux or vmlinuz.gz
> +
>
> If you are using a uncompressed vmlinux image then use following command
> to load dump-capture kernel.
> @@ -282,18 +303,19 @@
> --initrd=<initrd-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
> +
> Following are the arch specific command line options to be used while
> loading dump-capture kernel.
>
> -For i386 and x86_64:
> +For i386, x86_64 and ia64:
> "init 1 irqpoll maxcpus=1"
>
> For ppc64:
> "init 1 maxcpus=1 noirqdistrib"
>
> -For IA64
> - (To be filled)
> -
>
> Notes on loading the dump-capture kernel:
>
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