[U-Boot] [PATCH V2] i.MX28: Drop __naked function from spl_mem_init

Wolfgang Denk wd at denx.de
Tue Mar 20 09:39:29 CET 2012

Dear Stefano,

In message <4F683862.4030709 at denx.de> you wrote:
> > +	/* The following is "subs pc, r14, #4", used as return from DABT. */
> > +	const uint32_t data_abort_memdetect_handler = 0xe25ef004;
> Are we maybe becoming warning addicted ? I know the reason for this (GCC
> raises a warning "-fstack-usage not supported for this target"), you
> have already asked the gcc people about this issue, and I do not have an
> idea how to fix this warning in a different way as you did. This is a
> sort of self-modifying code.

In which way is this self-modifying code? I don't think so.

> However, the original code is quite easy to understand - I cannot say
> the same after the patch, we rely on the comment to understand something.

That's what comments are made for :-)

> Should we really fix such as warnings even if we generate some obscured
> code ? Wolfgang, what do you think about ?

Yes, we should fix warnings.  If you run a MAKEALL and can be sure
that any message printed is a new problem you will not miss it, and
act as needed.  If youy know that a build will pop up a number or
warnings, it's all too easy to miss if there is a new one - and
checking takes much more concentration.  This is to be avoided.

On the other hand, I agree that we should avoid obscure code as
well.  But then, to me the assembler code "subs pc, r14, #4" is
already obscure enough - I have to admit that I don't really grok it,
nor why this needs to be a __naked function.

My understanding is that to avoid the warning we can either use this
"pre-compiled constant instruction" trick, or we would have to create
a new assembler source file for this single instruction function.

When Marek and I discussed this, the constant seemed to be the
simplest approach (not the nicest, though).

If you don't like it, then we I think we will end up with a new tiny
assembler source file.  Would that be preferred by you?

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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