Re: [RFC PATCH] x86: make 64bit efi to use ioremap_cache for efi_ioremap

["huang ying" <huang.ying.caritas@gmail.com>]

On Sun, Oct 5, 2008 at 1:44 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Sat, Oct 4, 2008 at 2:35 AM, huang ying <huang.ying.caritas@gmail.com> wrote:
[...]
>> Using __va and efi_ioremap() here is to make EFI support compatible
>> with kexec. Because EFI provide only efi_enter_virtual_mode(), no
>> efi_leave_virtual_mode(), we should make EFI runtime memory area
>> mapped to same virtual memory area in original kernel and kexeced
>> kernel, so that the EFI runtime services can be used in kexeced
>> kernel.
>
> so need to make efi range all under direct-mapping like E820-RAM?

Some EFI runtime range is just some RAM area used by EFI runtime
services, they can be direct-mapped. Some EFI runtime range may be IO
MEM range used by EFI runtime services, it is possible that these IO
MEM range can not be direct-mapped. So I implement efi_ioremap() to
deal with them.

Best Regards,
Huang Ying