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Re: EFI-dualbooting OSX and Linux on iMac with T7400-CPU

From: bibo,mao
Subject: Re: EFI-dualbooting OSX and Linux on iMac with T7400-CPU
Date: Mon, 18 Dec 2006 11:31:27 +0800
User-agent: Thunderbird (Windows/20061025)

Eeri Kask wrote:
bibo,mao wrote:
 > There exists one bug in Linux kernel only EFI bios relative at
> <>
 > I do not know whether incorporates this bug.

Oh, I see.  This bug is not corrected in
As a side note, in contrast, in  "arch/x86_64/kernel/"  there are
seemingly no files having anything to do with efi.  Maybe this is of no
importance though.
x86_64 currently does not support EFI bios, there is no x86_64 efi
booloader and x86_64 kernel does not support EFI bios now. Soon x86_64
kernel patch and grub bootloader patch will be published out.

From your dmesg information, system boots from legacy bios. When machine
is powered on, EFI bios is loaded first and then lagacy bios is loaded if
there is no response.

 >> Maybe MacOS if booting from CD sets up some faked BIOS environment so
 >> Linux and X11 are in believing it is usual IBM-PC-hardware, but if
 >> booting with grub2 this is not the case and then linux fails?
 > I am not familiar with Mac machine, In general there exists two types of
 > bios. One is EFI bios, the other is legacy pc bios. I doubt that
 > syslinux-CD boots from legacy pc bios but not EFI bios. You can enter
 > "dmesg" command to find memory map information to judge which bios kernel
 > boots from.


I sincerely apologise for the long attachment in advance; here I send
you the dmesg output in full, most of it I do not understand.


    Eeri Kask


Bootdata ok (command line is root=/dev/sda5 BOOT_IMAGE=bzImage )
Linux version (address@hidden) (gcc version 4.1.1 (Gentoo 4.1.1))
#1 SMP PREEMPT Wed Dec 6 16:09:02 CET 2006
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
 BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000007f103000 (usable)
 BIOS-e820: 000000007f103000 - 000000007f304000 (ACPI NVS)
 BIOS-e820: 000000007f304000 - 000000007febe000 (ACPI data)
 BIOS-e820: 000000007febe000 - 000000007feef000 (ACPI NVS)
 BIOS-e820: 000000007feef000 - 000000007ff00000 (ACPI data)
 BIOS-e820: 000000007ff00000 - 0000000080000000 (reserved)
 BIOS-e820: 00000000f0000000 - 00000000f4000000 (reserved)
 BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved)
 BIOS-e820: 00000000fed14000 - 00000000fed1a000 (reserved)
 BIOS-e820: 00000000fed1c000 - 00000000fed20000 (reserved)
 BIOS-e820: 00000000fee00000 - 00000000fee01000 (reserved)
 BIOS-e820: 00000000ffe00000 - 0000000100000000 (reserved)
the memory map information shows that it is e820 map information,
it is legacy bios memory map information. Currently Linux only supports EFI bios on IA32 platform.


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