Re: [PATCH] target/s390x: Add a CONFIG switch to disable legacy CPUs

[Thomas Huth <thuth@redhat.com>]

On 14/06/2024 08.07, Christian Borntraeger wrote:
> 
> 
> Am 13.06.24 um 19:07 schrieb Thomas Huth:
>> Old CPU models are not officially supported anymore by IBM, and for
>> downstream builds of QEMU, we would like to be able to disable these
>> CPUs in the build. Thus add a CONFIG switch that can be used to
>> disable these CPUs (and old machine types that use them by default).
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   If you're interested, the PDF that can be downloaded from
>>   https://www.ibm.com/support/pages/ibm-mainframe-life-cycle-history
>>   shows the supported CPUs in a nice diagram
> 
> z13 is still supported so the patch needs to be fixed at least.

Oh, drat, I misread the diagram, indeed. 'should have looked at the table 
instead :-/

> Furthermore, z14 has the IBC/VAL cabability to behave like a z13,
> same for z15. (we do support VAL to N-2)

Hmm, so if z13 is still supported, and also has the possibility to do N-2, I 
assume the z114/196 and z12 should still be considered as non-legacy, too?

> I fail to see the value of this given how stable this code is.

As mentioned in the patch description, it's meant for downstream builds of 
QEMU where we'd like to avoid legacy devices and CPUs in the builds (it 
doesn't make sense to have support for e.g. z900 CPUs there).

  Thomas