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

H. Peter Anvin
2008-02-28T21:19:37Z

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