Re: [RFC] use realmode code to reserve end-of-conventional-memoryto 1MB

From: H. Peter Anvin
Date: Thu Feb 28 2008 - 16:19:38 EST


Ian Campbell wrote:
On Thu, 2008-02-28 at 14:28 +0100, Alexander van Heukelum wrote:
Instead of using early reservations inside the kernel code,
we could use the realmode code to modify the e820 memmap.
This patch shows what that would look like. I have not looked
at the case where the BIOS does not provide an e820 memmap
yet. Probably a full solution would need to create a fake
e820 memmap in that case.

An e820 is already faked up in machine_specific_memory_setup() if one
doesn't already exist.

Comments?

This won't work for Xen since the real-mode code never runs there. I
think it could be fixed in xen_memory_setup() though if native goes down
this route.


s/could/should/.

You need to set up your memory map more sensibly; it's not just the kernel, user space tries to access these areas too.

-hpa
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