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Re: efi Grub2 of Ubuntu 10.10 x64 fails to execute on qemu with -enable-

From: Vladimir 'φ-coder/phcoder' Serbinenko
Subject: Re: efi Grub2 of Ubuntu 10.10 x64 fails to execute on qemu with -enable-kvm
Date: Thu, 11 Nov 2010 23:26:29 +0100
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On 11/11/2010 07:54 PM, Adhyas Avasthi wrote:
> I get your point, but that just stops "some" people from using Grub2
> for EFI Development work and to look for other options.
If they are developpers and they care about GRUB supporting EFI+kvm,
it's a free software world, and patches are welcome. I just stated that
from where I sit (tram stop, and it rains) it has little point.
>  Unfortunately,
> people who also want to boot regular OSes on their EFI BIOSes
EFI isn't BIOS. EFI and BIOS are different kind of firmware.
What's the real point in running OS under X or Y firmware if once kernel
kicks in the difference is pretty small?
>  (besides
> their own OSes which they want to convert to pure EFI) suffer because
> regular OSes (at least Ubuntu) have chosen Grub 2 as their platform,
> and a lot of companies out their do wish to run Ubuntu in a VM. Some
> of my clients wish to develop certain EFI applications or run time OS
> applications using EFI,
What's the advantage over old good kernel modules? I fail to see any.
>  for which they have chosen Virtual Machines as
> their development platforms and wish to boot to Ubuntu on EFI on qemu.
> Without KVM, the guest is really not usable as it is very very slow.
> They do have their own BIOS ports and expose certain vendor specific
> Run Time services to use and expose to the users through the custom
> apps.
Why not simply move the relevant code from firmware (EFI, BIOS and so
on) to the custom app itself? It will make the handling and upgrade of
relevant functions way easier.
> Let me see if I can root cause the bug (err, workaround/issue) myself.
> I do need to make it work for the client as it is their requirement to
> boot a Linux OS in a VM on pure EFI world, so practically it is an
> issue whether we as a community choose to acknowledge it or not. 
The issue itself is obviously acknowledged but
a) The root cause is probably burried deep into the way CPU handles Blue
b) Priority is low (your priorities don't have to be the same as ours)
> As of
> now, KVM does execute all other x64 bit code successfully (including
> the entire 64-bit kernel), so I would put a little bit more faith on
> KVM. 
Only because it's optimised for this code to function. Qemu (w/o kqemu
or kvm) is the most accurate free emulator and second-best if you
consider non-free as well. But even qemu is completely accurate. As an
example I'm pretty sure that our video_cirrus which is coded for qemu
won't work with real Cirrus card as it is now. Also I spoke with
Carl-Daniel (coreboot dev and flashrom maintainer) and he agreed with it
and added that qemu even being very good has a number of flaws.
> Let me see why I crash using kvm on qemu-kvm-0.13.0. My host
> kernel is 2.6.32 but that should not matter because I have updated my
> kvm-kmod for that kernel anyway. Am compiling a new kernel to see if
> the issue still exists for 2.6.36 kernel.
> BTW, when you say you loaded Grub2, what does that mean? 
It means that I was able to load GRUB, have its shell, load Linux which
panic'ed because it couldn't find root (understandable since I had no
root= option or viable root partition at all)
> Does it mean
> you were able to boot to the OS as well? Or just see the Grub menu
> screen or command prompt? I am just curious what works with 0.12.5 and
You can have my ROM images at
Linux used comes from some debian package, can't say which one.
I suggest to first compare the CPUs, especially the extended page table
> I can try to put my Ubuntu DVD image as well to see if I can match
> what you have. Are there any command line parameters I can pass to the
> EFI Grub2 boot loader when I invoke it manually from the EFI Shell, to
> see any more information about the crash?
No but you can embed the config consisting of "debug=all"
>  Also, I haven't yet fully
> understood how to enable more debug (EFI BIOS dumps all debug I want
> on the serial port) from within the boot loader if I build it myself,
> any pointers on that will be useful.
> PS: I would still appreciate if I can ask questions on this mailing
> list while I debug this issue, and I can get some help where I am
> blocked.
You can ask the questions but a questions of kind "I'm stuck, can you
spend 5 hours on issue that is very low-priv for you?" isn't likely to
be answered. Be sure to get to the point, ideally producing a minimal
example which will give a motivation and make it easy to answer. For
more info refer:

Vladimir, sitting at tram stop, but tram should come any second now

Vladimir 'φ-coder/phcoder' Serbinenko

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