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Date: Fri, 04 May 2012 16:02:05 +0200
From: Christian Borntraeger <borntraeger@de.ibm.com>
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Subject: Re: [Qemu-devel] [PATCH 1/1] s390: IPL device for s390
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To: Alexander Graf <agraf@suse.de>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>, Jens Freimann <jfrei@linux.vnet.ibm.com>, Heinz Graalfs <graalfs@linux.vnet.ibm.com>, qemu-devel <qemu-devel@nongnu.org>

On 04/05/12 16:00, Christian Borntraeger wrote:
>>> An IPL (booting) on s390 of SCSI disks is done by a firmware component.
>>> Lets implement this scheme as an qemu device that also allows to
>>> configure the IPL like the HMC. We have a parameter iplid that
>>> refers to a disk device and a load parm that specifies the entry
>>> on the disk to be ipled. We also provide a default device
>>> if no -device s390-ipl statement is given.
>>
>> Any reason we can't do this in guest firmware code?
> 
> Conceptually guest firmware does not exist in the guest address space
> on s390. It is separate in a storage area called HSA. 
> (you could say the existing hardware is semi-hosted, you cant buy it bare 
> metal.
> Doing the boot code in guest address space will fail if the guest firmware
> address  collides with the addresses specified by a bootmap.

Or in other words, this code is closer to the real s390 boxes.