[Buildroot] [PATCH RESEND 0/2] Use bzip2 for X11 PFC font compression

[Aaron Sierra <asierra@xes-inc.com>]

----- Original Message -----
> From: "Thomas Petazzoni" <thomas.petazzoni@bootlin.com>
> Sent: Monday, July 13, 2020 2:32:25 PM

Hi Thomas,

Thanks for your review.

> Hello Aaron,
> 
> Thanks for this work!
> 
> On Mon, 13 Jul 2020 13:47:49 -0500
> Aaron Sierra <asierra@xes-inc.com> wrote:
> 
>> Gzip has been used as the default compressor for PCF fonts, but this
>> series changes the default compressor to bzip2 for a few reasons:
>> 
>> 1. Even with the latest gzip, these seemingly synonymous pipelines
>>    produce different output, but this issue does not exist with bzip2:
>> 
>>   $ cat /path/to/file | gzip > /path/to/file.gz
>>   $ gzip < /path/to/file > /path/to/file.gz
>> 
>> 2. Prior to gzip 1.10, the compression pipeline used with PCF fonts was
>>    not reproducible due to the implicit -N/--name injecting a timestamp:
>> 
>>   * cat /path/to/file | gzip > /path/to/file.gz
>> 
>> 3. The BR2_USE_WCHAR dependency of the gzip package tarnishes the appeal
>>    of using host-gzip to provide reproducible output.
> 
> This argument seems pretty weird. The fact that gzip needs
> BR2_USE_WCHAR on the target doesn't at all prevent from building
> host-gzip. We have plenty of host packages that need wchar packages,
> and we simply assume the host system as wide char support available.
> 
> So this third argument is a bit "moot", especially since
> host-xapp-mkfontscale already has a dependency on host-gzip, which
> builds a gzip 1.10, so it shouldn't be affected by the problem you
> describe.

OK, then maybe adding a host-gzip dependency would be the better solution.
I've found some evidence that this patchset isn't complete with respect to
X itself using bzip-compressed fonts :(

> So that leaves us with just argument (1), correct ?

Well, I think that (2) or (3) would be needed as the real justification for
switching compression mechanisms. Let me investigate the host-gzip path now
that I know that isn't a compatibility problem.

-Aaron
 
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com