Inlined.
On 28.11.2006, at 19:55, bibo,mao wrote:
Yoshinori K. Okuji wrote:
On Tuesday 28 November 2006 13:46, bibo,mao wrote:
> yes, x84_64EFI starts with 64-bit long mode and page enabled
(virtual
> address equals physical address) if it is x86_64 efi bios, it
is defined in
> section 2.3.4 of UEFI Specification Version 2.0.
>
> If kernel image is bzImage, x64 efi bootloader need switch to
32 bit
> protect mode(or real mode) from 64 bit long mode, and if kernel
image is
> gzipped/plain format, efi bootloader can directly jump to 64-
bit kernel
> entry address without mode switch.
Thanks for your detailed information. So does it mean that GRUB
needs to
provide a PE32+ application to EFI, if it is on x86_64? Or does it
understand
PE32? More information is welcome.
Now I tried on x86_64, it seems that x86_64 efi bios does not
support PE32
format, PE32+ application should be provided.
Yes. Grub for x64 EFI should be a PE32+ image.
BTW, in the current implementation, GRUB skips real mode setup
code in Linux
and directly jumps to a protected mode entry on EFI. Can we use
the same
trick with bzImage on x86_64? Mode switching is not difficult, but
if we can
omit it, that would be much easier to implement.
On i386 efi platform, real mode setup code can be skipped with
bzImage. But on
x86_64 efi platform with bzImage format, it seems that it need
switch to 32-bit
protect mode at least.
We can discard mode switching at beginning so that it can boot
kernel image with
gzipped format. Mode switching code is not difficult and very
small, the problem
is that x86_64 bootloader(pe32+) can be loaded at address beyond
4G, but mode
switching code must be within 4G, also self-uncompressed bzimage
code possibly
flushes mode switching code. I do not know which address is safe to
put switching code, how about 0x7c00?
That is not a problem. AllocatePages() in the UEFI runtime services
can be told to allocate memory below a certain address by passing
AllocateMaxAddress as the EFI_ALLOCATE_TYPE. The UEFI specification
is your friend :) – http://www.uefi.org/
thanks
bibo,mao
Okuji
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/grub-devel
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/grub-devel
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/grub-devel
