Re: [Qemu-devel] [PATCH] multiboot: Prevent loading of x86_64 images

[Alexander Graf]

On 19.08.2010, at 13:36, Adam Lackorzynski wrote:

> 
> On Thu Aug 19, 2010 at 13:27:32 +0200, Alexander Graf wrote:
>> 
>> On 19.08.2010, at 13:24, Adam Lackorzynski wrote:
>> 
>>> A via -kernel supplied x86_64 ELF image is being started in 32bit mode.
>>> Detect and exit if a 64bit image has been supplied.
>> 
>> According to the multiboot spec, this is the expected behavior, no? At least 
>> Xen does it that way...
> 
> Yes, but then the supplied ELF-image should say it's a 32bit one and
> switch to 64bit mode itself. That's at least how we do load a 64bit
> kernel.

Hrm - maybe you're right:

busu:~ # readelf -a /boot/xen
ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32

What does the spec say here? What does grub do?


Alex