[PATCH v2 0/8] Initial implementation of kdump for ARM

[Russell King - ARM Linux]

On Mon, Jul 05, 2010 at 05:37:11PM +0200, Per Fransson wrote:
> On 07/05/2010 04:19 PM, Russell King - ARM Linux wrote:
> > On Mon, Jul 05, 2010 at 04:05:56PM +0200, Per Fransson wrote:
> >> Well, I had another suggestion in my last mail.
> > 
> > Which is going to need per-CPU type support in order to achieve.  Do
> > we really want to implement relocate_new_kernel for each of the 24
> > CPU types which we currently support?
> > 
> 
> Perhaps not. Couldn't the variable delay be macrofied then, i.e. a
> macro like
> 
> MMU_DISABLED_DELAY_AND_EXEC(<asm instr>)
> 
> which would do nothing for an appropriate amount of time and put the
> instruction in the last MMU mapped slot?

There is no "appropriate amount of time" - some CPUs depend on many
effects that a "3 nops and you'll be fine" approach doesn't work.

Also, what about kernels that support multiple different CPU types.