Re: [PATCH] Fix VMI crash on boot in 2.6.27+ kernels

From: H. Peter Anvin
Date: Tue Dec 09 2008 - 20:53:29 EST


Yinghai Lu wrote:
>
> VMI initialiation can relocate the fixmap, causing early_ioremap
> to malfunction if it is initialized before the relocation. The
> ioremap area is low enough in virtual address space that no actual
> collision occurs, however, because the pagetables for it were not
> allocated under VMI mode, the pagetable updates are dropped by
> the hypervisor as irrelevant, resulting in a crash on boot.
>

I have mentioned in the past that I think the very concept of relocating
the fixmap to be utterly braindead. Instead, I believe we should locate
it low in kernel space so it doesn't have to be relocated. It's
unfortunately a relatively large change.

-hpa
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