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Date: Tue, 24 Nov 2009 13:26:45 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 12/13] Add zipl bootloader interpreter
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To: Alexander Graf <agraf@suse.de>
Cc: Carsten Otte <cotte@de.ibm.com>, qemu-devel@nongnu.org, Aurelien Jarno <aurelien@aurel32.net>

Alexander Graf wrote:
> On 24.11.2009, at 19:53, Anthony Liguori wrote:
>
>   
>> Alexander Graf wrote:
>>     
>>> The default bootloader on S390 is zipl. Because we don't emulate normal S390
>>> hardware we need to write our own parser for the bootloader configuration,
>>> so we can boot off real hard disks.
>>>
>>> This patch adds a pretty simple implementation of such an interpreter. It only
>>> supports 512 bytes sector sizes, always boots the default entry and doesn't
>>> work with reboots yet. But it's better than nothing.
>>>  
>>>       
>> This is a bit unfortunate.  Wouldn't it be better to write a custom version of zipl that ran in the guest?
>>     
>
> Yeah, I've been struggling quite a bit with this myself. Writing a custom version that runs in the guest means we have to create
>
> 1) extboot
> 2) input backdoor
>
> Or implement virtio in that custom version. That sounds like a pretty huge project.
>
> So I decided to go for the easy way for now and hopefully migrate to an in-guest version later.
>   

Can't you just use kboot?

Use a kernel loader to load the kboot module/initrd, include kboot as 
our firmware, then let kboot do the magic to launch the real linux 
kernel from disk.

Regards,

Anthony Liguori