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

[bibo,mao]

Eeri Kask wrote:
> bibo,mao wrote:
>  >> menuentry "MacOSX" {
>  >>   set root=(hd0,2)
>  >>   chainloader /System/Library/CoreServices/boot.efi
>  >> }
>  >>
>  >> menuentry "GNU/Linux" {
>  >>   set root=(hd0,5)
>  >>   linux /boot/vmlinuz root=/dev/sda5
>  >> }
>  >>
>  > There is no initrd option in your menu, I do not know whether it can
>  > successfully boot up without initrd option with grub2. you can enter
>  > into rescue mode(command-line mode), and enter commands like this:
>  > $linux /boot/vmlinuz root=/dev/sda5
>  > $initrd /boot/xxx
>  > $boot
>  >
>  > And what is your linux kernel version?
>
> 2.6.18.5.
There exists one bug in Linux kernel only EFI bios relative at
http://marc.theaimsgroup.com/?l=linux-kernel&m=116157536316034&w=2
I do not know whether 2.6.18.5 incorporates this bug.

> initrd is in my case in fact not needed;  I compiled ata_piix and ext3
> drivers, and everything inbetween directly into the kernel, so if
> correctly loaded, it should be able to access /dev/sda5 and retrieve
> /sbin/init from the hard disk; then everything else comes from there as
> well.
>
> Currently I am a little puzzled, as grub2 loads and executes MacOS-X
> boot.efi correctly, but if trying linux, then linux stops somewhere.
> As next, if burning the same kernel image as a bootable syslinux-CD,
> linux gets loaded and executed as one would expect.
> With the "nv" driver even X11 runs in full 1920x1200 resolution on
> iMac-T7400 excellently  (nvidia proprietary driver builds, starts and
> runs without complaints, but shows "black pixels" only :-).
>
> 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.

thanks
bibo, mao

> Momentarily I am not convinced it is a grub2 issue.
>
> Greetings,
>
>     Eeri Kask
>
>
>
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