Re: [PATCH v2 08/20] x86, ACPI: Find acpi tables in initrd early from head_32.S/head64.c

H. Peter Anvin
2013-04-04T20:26:54Z

On 03/10/2013 03:25 AM, Pekka Enberg wrote:
>
> What is preventing us from making the 64-bit variant also work in flat
> mode to make the code consistent and not hiding the differences under
> the rug? What am I missing here?
>

There is no such thing as "flat mode" in 64-bit mode. We use a #PF
handler to emulate it, but we add the normal kernel offset when doing so.

In the 32-bit case the problem is that the kernel offset is not
available while in linear mode. It *could* be created using segment
bases, but that would break Xen, I'm pretty sure, and possibly some
other too-clever environments.

-hpa