Re: [patch 07/15] Basic x86_64 support

[Andi Kleen]

On Thu, Aug 04, 2005 at 08:06:36AM -0700, Tom Rini wrote:
> > 
> > Why can't you run on x86-64 early? 
> 
> As I said earlier:
> "
> > If you want to run gdb earlier you need to do it without a tasklet.
> 
> We really would like to try again once stacks are setup (IOW, once
> if ((&__get_cpu_var(init_tss))[0].ist[0])) is true).
> "
> 
> IOW, when we parse the params on x86_64 this isn't true (or rather it
> wasn't true as of 2.6.9'ish, if this has changed I'd be glad to retest
> things).

The ISTs are set up for the boot processor extremly early - even
before start_kernel. But they are useless before trap_init()
runs because you won't get any exceptions that need an IDT (or rather
they will all still point to the early exception handler that just panics) 

-Andi

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