[Mesa-dev] [PATCH] configure.ac: Allowing building without shader cache without zlib.

[Timothy Arceri]

On 09/03/17 07:30, Marek Olšák wrote:
> On Wed, Mar 8, 2017 at 9:14 PM, Vinson Lee <vlee at freedesktop.org> wrote:
>> On Sat, Mar 4, 2017 at 3:42 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>>> On 4 March 2017 at 22:43, Vinson Lee <vlee at freedesktop.org> wrote:
>>>> On Sat, Mar 4, 2017 at 5:24 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>>>>> On 4 March 2017 at 22:13, Vinson Lee <vlee at freedesktop.org> wrote:
>>>>>> Fixes: 85a9b1b562b6 ("util/disk_cache: compress individual cache entries")
>>>>>> Signed-off-by: Vinson Lee <vlee at freedesktop.org>
>>>>>> ---
>>>>>>  configure.ac | 3 +--
>>>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/configure.ac b/configure.ac
>>>>>> index 943bc05adcd6..3526849b6dd2 100644
>>>>>> --- a/configure.ac
>>>>>> +++ b/configure.ac
>>>>>> @@ -786,7 +786,7 @@ dnl See if posix_memalign is available
>>>>>>  AC_CHECK_FUNC([posix_memalign], [DEFINES="$DEFINES -DHAVE_POSIX_MEMALIGN"])
>>>>>>
>>>>>>  dnl Check for zlib
>>>>>> -PKG_CHECK_MODULES([ZLIB], [zlib >= $ZLIB_REQUIRED])
>>>>>> +PKG_CHECK_MODULES([ZLIB], [zlib >= $ZLIB_REQUIRED], [DEFINES="$DEFINES -DENABLE_SHADER_CACHE"], [:])
>>>>>>
>>>>> Why - is it causing breakage or any system ?
>>>>>
>>>>> Afaict we really want to have this tested thoroughly and silently
>>>>> disabling it is a very bad idea.
>>>>>
>>>>> -Emil
>>>>
>>>> Older distros have a zlib older than 1.2.8.
>>>
>>> Tim I think you had something in mind about such cases, hehe ;-)
>>>
>>> But seriously, seems like enterprise Linuxes are stuck with very old ones:
>>> RHEL4 - 1.2.1
>>> RHEL 5/6 - 1.2.3
>>> SLES 10/11 - 1.2.3
>>>
>>> Tim, I'll leave the rest to you - how/worth using third party package,
>>> dropping to 1.2.3 or other ?
>>> I'm leaning towards 1.2.3, unless there's some serious down sides with it.
>>>
>>> -Emil
>>
>> Is downgrading to zlib 1.2.3 okay? Otherwise, can we add support to
>> not build the shader cache in the autoconf build?
>
> Users building from source can build zlib from source too. I don't see
> a problem with that. If we wanna make it easier for them, we can allow
> zlib 1.2.3 as well. In any case, the shader cache should remain
> enabled.
>
> Marek

I made a comment about 1.2.3 support in the bug report [1]. IMO we 
should not be setting lib requirements to versions that have not seen 
regular testing with Mesa, and in the process exposing us to a larger 
range of potential versions to test against should a bug appear. Also I 
think it's outside of our responsibility to worry about distros using 
heavily patched very out of date libraries.

For example RHEL 6 ships 1.2.3-28, this get's us into a situation where 
we are not really recommending 1.2.3 but the heavily patches variants 
shipped in these distros. I already think we are are doing the wrong 
thing by setting GCC at 4.2.0 (for BSD's forked GCC variant) I'd rather 
not start doing it for other software.

For what it's worth I know for a fact that Firefox does not support the 
out of date GTK versions shipped with RHEL 6 and Redhat needs to keep 
their own patches to keep things working on these GTK versions (among 
the many other issues they face).

So as much as I appreciate the testing done by Vinson and don't want to 
make things too difficult, I believe the correct solution would be that 
anyone building on RHEL 6 carry their own patch to downgrade to 1.2.3.

Tim

[1] https://bugs.freedesktop.org/show_bug.cgi?id=100093