Re: [Qemu-devel] [PATCH] configure: Warn about deprecated hosts

[Thomas Huth]

On 17.03.2017 14:22, Peter Maydell wrote:
> On 17 March 2017 at 13:19, Thomas Huth <address@hidden> wrote:
>> On 17.03.2017 12:52, Peter Maydell wrote:
>>> On 17 March 2017 at 11:49, Daniel P. Berrange <address@hidden> wrote:
>>>> On Fri, Mar 17, 2017 at 11:08:22AM +0000, Peter Maydell wrote:
>>>>> We plan to drop support in a future QEMU release for host OSes
>>>>> and host architectures for which we have no test machine where
>>>>> we can build and run tests. For the 2.9 release, make configure
>>>>> print a warning if it is run on such a host, so that the user
>>>>> has some warning of the plans and can volunteer to help us
>>>>> maintain the port if they need it to continue to function.
>>
>> I like your patch! ... but instead of completely aborting with
>> "Unsupported host OS" when an unexpected host operating system has been
>> detected, I'd maybe only print a warning and continue the configure
>> process - in case it is a POSIX-compatible system, there is at least a
>> small chance that QEMU can be compiled there.
> 
> That code path tries to enable all the Linux specific stuff
> (including KVM and linux-user and so on) and puts linux-headers/
> on the include path. It seems very unlikely that it will actually
> work even if in theory a generic-POSIX OS might be able to build
> QEMU somehow.

Ah, sorry, you got me slightly wrong. I think it is a good idea that you
replaced the "*)" with "Linux)" in your patch. I rather meant to simply
do "echo" instead of "error_exit" in the new "*)" case.

I now just tried to build QEMU with such a "fake" generic POSIX system
(by hacking configure to not recognize "Linux"), and seems like QEMU
properly compiles in that case - but linking fails because net/tap.c is
missing a tap backend.

So you're right, currently it is not possible to build QEMU on unknown
host systems, i.e. the "error_exit" is indeed justified there (though I
think it would be maybe be possible to also add stubs for missing tap
functions to make it work).

 Thomas