plugins/Makefile: use files to avoid hitting ARG_MAX during build

[MatthewCroughan]

When adding more modules to the build, ar will be passed far more .o files as arguments on the command line than the limits specified by most host kernels by default, which will cause the build to fail with /bin/bash: Argument list too long

Using xargs can show you what these limits are on POSIX systems, e.g:

$ xargs --show-limits
Your environment variables take up 6774 bytes
POSIX upper limit on argument length (this system): 2088330
POSIX smallest allowable upper limit on argument length (all systems): 4096
Maximum length of command we could actually use: 2081556
Size of command buffer we are actually using: 131072
Maximum parallelism (--max-procs must be no greater): 2147483647

[falkTX]

are you actually hitting this limit?

I dont understand what you are trying to do with the "file > " syntax

[MatthewCroughan]

Yeah, if you just add a few more submodules and compile a headless build, it will result in a string length far too large to work, ultimately throwing that bash error, due to the max argument size in the host kernel.

I dont understand what you are trying to do with the "file > " syntax

The file syntax thing confused me as well, but it's a feature of Make that I discovered in fixing this https://www.gnu.org/software/make/manual/html_node/File-Function.html

All we're doing is putting PLUGIN_OBJS, into a file, so that ar crs can read it from this file (something it supports), instead of trying to pass a 2MB~ string to the ar command via bash, which runs into these limits.

[multivac61]

It fails on mac due to inconsistencies between the GNU and BSD versions of make and ar (binutils). I can confirm when using GNU versions, this PR builds on my local mac machine.

[falkTX]

we cant assume the GNU version. Cardinal builds on BSD too which has the same situation

[MatthewCroughan]

Does that mean that BSD ar and make cannot read lists of args from files? If so, I don't see how this is going to be resolved on those platforms

[MatthewCroughan]

We should be able to use cat | xargs | ar but first PLUGIN_OBJS needs to get into a file, which is the thing that Make on BSD doesn't support

[MatthewCroughan]

@falkTX I dare not ask what happens on Haiku. Where is your Haiku CI? :D