Re: Oldest supported Xen version in upstream QEMU (Was: Re: [Minios-devel] [PATCH v2 0/15+5+5] Begin to disentangle libxenctrl and provide some stable libraries)

[Juergen Gross <jgross@suse.com>]

On 09/23/2015 04:09 PM, Konrad Rzeszutek Wilk wrote:
> On Wed, Sep 23, 2015 at 09:29:10AM +0100, Ian Campbell wrote:
>> On Tue, 2015-09-22 at 22:31 +0100, Stefano Stabellini wrote:
>>> The oldest Xen version I build-test for every pull request is Xen 4.0.0,
>>> I think it is very reasonable to remove anything older than that.
>>> I am OK with removing Xen 4.0.0 too, but I would like a warning to be
>>> sent ahead of time to qemu-devel to see if anybody complains.
>>
>> There is not much point in removing <=3.4 support and keeping 4.0, since
>> 4.0.0 was the last one which used a plain int as a handle, anything older
>> than 4.0.0 is trivial if 4.0.0 is supported.
>>
>> One approach I am considering in order to keep 4.0.0 support and earlier
>> was to turn the "int fd" for <=4.0 into a pointer by having the open
>> wrapper do malloc(sizeof int) and the using wrappers do xc_foo(*handle).
>>
>> This way all the different variants take pointers and we have less hoops to
>> jump through to typedef everything in the correct way for each variant.
>>
>> If you would rather avoid doing that then I think dropping 4.0.0 support
>> would be the way to go and I'll send a mail to qemu-devel.
>
> Perhaps to help in killing the 4.0.0 support - Linux pvops can't work
> with Xen 4.0.0 - sadly I don't recall the details but I think it was missing
> an hypercall.

Are you sure? On the Xen developer summit this year I asked a guy from
Amazon whether they are testing upstream pvops kernels on all Xen
versions they support, and he confirmed that. And they do support Xen
4.0 and older.


Juergen