Re: [RFC PATCH 0/8] Module and ARM Module updates and fixes

From: David Dgien <dgienda125@gmail.com>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [RFC PATCH 0/8] Module and ARM Module updates and fixes
Date: Wed, 17 Jun 2020 21:54:55 -0400	[thread overview]
Message-ID: <20200618015455.GA9887@fizzbox.localdomain> (raw)
In-Reply-To: <20200617134538.GC11869@pengutronix.de>

Hi Sascha,

On Wed, Jun 17, 2020 at 03:45:38PM +0200, Sascha Hauer wrote:
> Hi David,
> 
> On Tue, Jun 16, 2020 at 11:43:56PM -0400, David Dgien wrote:
> > This series fixes various bugs and bit-rot issues with the module
> > loading code. It also ports a couple of modules features from the Linux
> > kernel: arch specific section fixups, and module PLTs for ARM modules,
> > to contain veneers for 'bl' instructions.
> > 
> > There are two things in this series I'm looking for feedback on:
> > Linux implements module_frob_arch_sections as a weak symbol for the
> > default case. I didn't see any other "weak" functions in barebox, so I
> > wasn't sure if using that was acceptable.
> 
> For things that are really mutually exclusive like different
> implementations on different architectures I think weak functions are
> ok. They are not ok as a quick hack for hooking something into something
> though.
> 

I'll make the change to a weak function here in a v2, since it will be a
bit cleaner.

> > Since the Kconfig
> > HAVE_MOD_ARCH_SPECIFIC already exists as part of the change, I just used
> > that to define a static inline default implementation, but using a weak
> > function would make that slightly cleaner.
> > 
> > And in the patch that added the init macros to module.h, I wasn't sure
> > if it would be okay to pollute init.h with the #ifndef MODULE
> > directives, so instead I just #undef'd all of the initcalls before
> > redefining them in module.h.  If it's okay to add the #ifndef MODULE to
> > init.h, that would be significantly cleaner than the current
> > implementation.
> 
> I think it's ok to add #ifndef MODULE to init.h

Same as above.

> 
> Anyway, what do you need modules for? Do you have a good reason or is it
> just for the fun of it?

I'm working on a project that wants to use barebox as a very lightweight
OS replacement. We're using modules to allow loading user code with
controlled access to hw interfaces via exported driver symbols.

-- David Dgien

> 
> Sascha
> 
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