Re: [patch v2 03/10] kdump: Add size to elfcorehdr kernel parameter

Vivek Goyal
2011-08-02T18:55:01Z

On Tue, Aug 02, 2011 at 11:08:07AM +0200, Michael Holzheu wrote:
> Hello Vivek,
>
> #On Mon, 2011-08-01 at 16:36 -0400, Vivek Goyal wrote:
> > On Wed, Jul 27, 2011 at 02:55:07PM +0200, Michael Holzheu wrote:
> > > From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
> > >
> > > Currently only the address of the pre-allocated ELF header is passed with
> > > the elfcorehdr= kernel parameter. In order to reserve memory for the header
> > > in the 2nd kernel also the size is required. To pass the size with this
> > > patch the syntax of the kernel parameter is extended as follows:
> > >
> > > elfcorehdr=[size[KMG]@]offset[KMG]
> > >
> > > This change is backward compatible because elfcorehdr=size is still allowed.
> >
> > Generally vmcore parses elfcorehdr to figure out the sizes. kexec-tools
> > knows about it and relevant memory is excluded from second kernel's map
> > with the help of memmap= command line option.
> >
> > Can you please mention that this is only s390 specific requirement as
> > there are no memmap= equivalent options and somehow dump tools wants
> > to know how big the elf header size is?
>
> I updated the description:
>
> Currently only the address of the pre-allocated ELF header is passed with
> the elfcorehdr= kernel parameter. In order to reserve memory for the header
> in the 2nd kernel also the size is required. Current kdump architecture
> backends use different methods to do that, e.g. x86 uses the memmap= kernel
> parameter. On s390 there is no easy way to transfer this information.
> Therefore the elfcorehdr kernel parameter is extended to also pass the size.
> This now can also be used as standard mechanism by all future kdump
> architecture backends.
>
> The syntax of the kernel parameter is extended as follows:
>
> elfcorehdr=[size[KMG]@]offset[KMG]
>
> This change is backward compatible because elfcorehdr=size is still allowed.
>
> Ok?

Yes, this one looks ok.

Thanks
Vivek