Re: [Qemu-devel] [PATCH v2 0/9] configure: Fix softmmu --static linking

[Philippe Mathieu-Daudé]

On 7/1/19 4:36 PM, Daniel P. Berrangé wrote:
> On Fri, Jun 14, 2019 at 12:07:09PM +0200, Philippe Mathieu-Daudé wrote:
>> Hi,
>>
>> Apparently QEMU static linking is slowly bitroting. Obviously it
>> depends the libraries an user has installed, anyway it seems there
>> are not much testing done.
> 
> Bitrotting implies that it actually worked in the first place.
> 
> AFAIK, configure has never been capable of auto-enabling the
> correct set of libraries for static linking, if you have the
> equiv dyn libraries present.
> 
> I always assumed that anyone who is static loinking QEMU is
> passing a big long list of --disable-XXXX args to turn off
> all the 3rd party libs for which they don't have a static
> build present.
> 
>> This series fixes few issues, enough to build QEMU on a Ubuntu
>> 18.04 host.
>>
>> Peter commented on v1:
>>
>>   The main reason for supporting static linking is so we can build
>>   the user-mode emulators. Almost always the problems with
>>   static linking the softmmu binaries and the tools are
>>   issues with the distro's packaging of the static libraries
>>   (pkg-config files which specify things that don't work for
>>   static is a common one).
>>
>>   So we could put in a lot of checking of "is what pkg-config
>>   tells us broken". Or we could just say "we don't support static
>>   linking for anything except the usermode binaries". We
>>   should probably phase in deprecation of that because it's
>>   possible somebody's using it seriously, but it seems like
>>   a fairly weird thing to do to me.
>>
>> I share his view on this (restricting static linking to qemu-user)
>> but since the work was already done when I read his comment, I still
>> send the v2.
> 
> I share Peter's view that we ought to restrict static linking to be
> allowed exclusively for user-mode-only builds of QEMU. This is a use
> case with a compelling reason to need static builds. It is not bitrotting
> as the main distros all do a static user-mode only QEMU build, alongside
> the main everything, fully dynamic build.
> 
> Static builds of system emulators & other tools get essentially no
> testing by developers, distros, or our CI systems. If they do work
> it is largely by luck, and likely requires the user to pass many
> --disable-XXX flags. While your patches do make configure a bit
> nicer in this respect, if we're going to deprecate static builds
> of non-user-mode parts, then making static builds easier feels
> undesirable.

OK, I agree then.

> 
> Lets just get a deprecation warning in right now for this imminent
> release.
> 
> Regards,
> Daniel
>