Re: [Qemu-devel] [PATCH 1/1] s390: IPL device for s390

[Alexander Graf]

On 04.05.2012, at 16:02, Christian Borntraeger wrote:

> 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.

Yeah, I see the point. I'd really like to get Anthony's comments on this one 
first though.


Alex