Re: [Buildroot] [PATCH] package/mono: allow to select which folders to install to target

[Giulio Benetti <giulio.benetti@benettiengineering.com>]

Hello Thomas,

On 31/10/22 13:25, Thomas Petazzoni wrote:
> Hello Giulio,
> 
> On Wed, 19 Oct 2022 01:46:17 +0200
> Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:
> 
>> At the moment all APIs folders are copied to target increasing the size of
>> rootfs of ~190MB. Allow to select which API folders we want to copy to
>> target to shrink rootfs down.
>>
>> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
> 
> Thanks for proposing this.
> 
> Practically speaking, could you describe which folders are needed in a
> typical scenario you've had?

One scenario I'm facing right now is:
drwxr-xr-x   4 giuliobenetti giuliobenetti 16384 ott 26 01:26 4.5
drwxr-xr-x 145 giuliobenetti giuliobenetti 12288 ott 26 01:20 gac
drwxr-xr-x   2 giuliobenetti giuliobenetti  4096 ott 26 01:22 lldb

And the total is 95MB big.
gac/ is ~56MB and that's mandatory in my case.
4.5/ is ~36MB
lldb/ is only 5K

While copying all directories is ~195MB so I was wrong, we don't save
~190MB, but anyway we save almost 100MB that for size costraint systems
and most of all for production programming save time. The latter is why
I need it most of all.

> Here, I have these ones:
> 
> drwxr-xr-x   2 thomas thomas  4096 oct.  25 22:58 2.0-api
> drwxr-xr-x   2 thomas thomas  4096 oct.  25 22:58 3.5-api
> drwxr-xr-x   2 thomas thomas  4096 oct.  25 22:56 4.0
> drwxr-xr-x   2 thomas thomas 12288 oct.  25 22:58 4.0-api
> drwxr-xr-x   4 thomas thomas 16384 oct.  25 22:58 4.5
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.5.1-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.5.2-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.5-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.6.1-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.6.2-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.6-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.7.1-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.7.2-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.7-api
> drwxr-xr-x   3 thomas thomas 12288 oct.  25 22:58 4.8-api
> drwxr-xr-x 145 thomas thomas 12288 oct.  25 22:56 gac
> drwxr-xr-x   2 thomas thomas  4096 oct.  25 22:56 lldb
> drwxr-xr-x   3 thomas thomas  4096 oct.  25 22:56 mono-configuration-crypto
> drwxr-xr-x   2 thomas thomas  4096 oct.  25 22:56 monodoc
> drwxr-xr-x   3 thomas thomas  4096 oct.  25 22:56 msbuild
> drwxr-xr-x   6 thomas thomas  4096 oct.  25 22:56 xbuild
> drwxr-xr-x   4 thomas thomas  4096 oct.  25 22:56 xbuild-frameworks
> 
>> +config BR2_PACKAGE_MONO_SPECIFY_FOLDERS_TO_INSTALL
>> +	bool "Specify folders to install to target"
>> +	help
>> +	  Allow to specify which Mono folder to install to target
> 
> I don't really have a very good suggestion, but I don't like the name
> of the option. We rarely have option names that are "sentences", i.e
> "specify folders to install" is a sentence.
> 
> Should we instead have a single string option
> BR2_PACKAGE_MONO_INSTALL_LIB_DIRS, which is empty by default. When
> empty, it means all folders are installed. Otherwise, only the
> specified folders are installed.

Yes, I can do like that.

> The other obvious question is whether this shouldn't simply be left as
> something to do in a post-build script. Even though I admit that
> reducing 190 MB down to something reasonable can be seen as something
> that is almost mandatory.

~100MB after recalculating. Anyway it's a bit odd to create ad hoc
script to remove 29 folders an keep only 3. Usually I expect a mono user
to write an application using only 1 API version.

> Or alternatively, do we have a better way, where we could automate this
> selection of which folders are needed?

In the beginning I thought that mono provided such possibility in its
build system but it's not like that, check:
https://github.com/mono/reference-assemblies/blob/680013abda911528f6befca67eed5669d80c85d5/Makefile

That is why I've ended up with this solution. Honestly I wanted to avoid
to even install these dll files to host/ but it's not possible.
Otherwise I have to patch the Makefile and in the end having 100M on
host I don't think is a problem.

-- 
Giulio Benetti
CEO/CTO@Benetti Engineering sas
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