Re: Booting 64-bit Linux on a Macbook5,2

[Colin Watson]

On Thu, Sep 23, 2010 at 12:06:37PM -0400, Patrick Doyle wrote:
> On Thu, Sep 23, 2010 at 10:01 AM, Colin Watson <address@hidden> wrote:
> > On Thu, Sep 23, 2010 at 09:47:44AM -0400, Patrick Doyle wrote:
> >> reading around, it seems that some folks have been able to boot with
> >> full capabilities (i.e. ACPI and both cores) when booting via EFI.
> >
> > I'm afraid I don't know how you might do that.  The best way to find out
> > why your system is hanging at boot is to attach a serial console to it,
> > if you can, and boot it with console=ttyS0 so that you can see the early
> > console messages.
> 
> Alas, my MacBook doesn't have a built in serial port.  I suspect that
> trying to get early console messages out through a USB serial port
> dongle (especially the cheap Radio Shack one that I have) is doomed to
> frustration.
> 
> OTOH, I have seen references to certain kernel command line parameters
> that make me think that a) EFI provides some sort of console API, and
> b) that Linux might have some sort of support for output to that
> console.  I'll add that to the list of things to look into.

In both cases (USB serial and EFI console), Linux supports console
output, but it isn't initialised early enough to catch oopses early on
in the boot process.

> > To me it sounds as if your machine has 64-bit EFI but that for some
> > reason the 64-bit kernel oopses at boot, before the console comes up.
> > I've seen this before and a serial console is about the only practical
> > way to debug it.
> 
> So, if my 64-bit EFI can boot a 64-bit grub (which seems to be the
> case), can I reasonably expect to boot either a 32 or a 64 bit kernel
> from grub?  Or should I only be able to boot a 64 bit kernel?

If everything is working correctly, then it should be possible to boot
either a 32-bit or a 64-bit kernel, but only the 64-bit kernel will
operate in EFI mode.

> >> This might not be the correct forum to ask this, but does anybody know
> >> what installing the "grub-efi-amd64" package really does for Ubuntu?
> >> Does it replace the grub-pc package that was presumably installed off
> >> the CD?
> >
> > On Ubuntu 10.04 LTS, grub-efi-amd64 installs the files but you have to
> > install the actual boot loader yourself.  On Ubuntu 10.10, it should
> > install the boot loader as well.  In both cases, it conflicts with
> > grub-pc - you can only have one or the other installed at once.
> 
> Just to make sure I'm understanding this correctly, should I do
> something vaguely similar to:
> 
> $ apt-get remove grub-pc
> $ apt-get install grub-efi-amd64
> $ grub-install /dev/sda3
> 
> ... if I want an EFI aware, 64-bit grub installed as my bootloader?

You don't need to explicitly remove grub-pc, since grub-efi-amd64
already conflicts with it.  grub-install will only work on 10.10, and on
EFI it doesn't take a device argument - instead it creates a grub.efi
image (there are a few possible names) and puts it in a particular
place.  On 10.04, you'll have to look up the documentation on
grub.enbug.org.  I strongly suggest looking through that documentation
anyway to orient yourself.

If you're already expecting to place an image in /efi/grub on your OS X
file system, then you might be better off following the wiki
instructions anyway ...

> If I do that, what should I expect to be differerent than the grub-pc
> bootloader that was (presumably) installed when I installed Ubuntu?

You get a new and exciting host of problems, since EFI mode is in
general less well-tested. :-)

> >> Should I be using that instead of compiling my own version of
> >> grub-1.98 (in a VMware box on my Mac) and placing my own version in
> >> /efi/grub?
> >
> > Well, it would probably at least save you compiling it.
> 
> Right now, when I compile it, I do so in order to produce a set of
> files that I can place in /efi/grub on my MacOS file system.  If I
> install grub-efi-amd64, it will be installed in the partition and in
> files on my Linux file system,

Sure, but you can always copy the resulting image around.

Cheers,

-- 
Colin Watson                                       address@hidden