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

[Jay Lan <jlan@sgi.com>]

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=256M@0
> +  or
> +  crashkernel=256M
> +
> +  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=128M@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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> https://lists.osdl.org/mailman/listinfo/fastboot

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