[PATCH] firmware: handle firmware files being links correctly

[Sascha Hauer]

On Wed, Sep 17, 2025 at 12:21:57PM +0200, Ahmad Fatoum wrote:
> On 9/17/25 11:58 AM, Sascha Hauer wrote:
> > Sometimes firmware files can be links. When rebuilding barebox correctly
> > rebuilds the firmware when file the link points to is updated, but the
> > firmware is not rebuilt when the link itself is changed to link to
> > another file.
> 
> This is surprising. I though GNU make looks at the mtime of the destination.

It does, but in this case it should also consider the timestamp of the
link itself, not the destination.

> > @@ -80,7 +82,7 @@ filechk_fwbin = { \
> >  	echo "    .p2align ASM_LGPTR"				;\
> >  	echo ".global _fw_$(FWSTR)_sha_start"			;\
> >  	echo "_fw_$(FWSTR)_sha_start:"				;\
> > -	echo "    .incbin \"$(fwobjdir)/$(FWNAME).sha.bin\""	;\
> > +	echo "    .byte $${SHA}"				;\
> >  	echo ".global _fw_$(FWSTR)_sha_end"			;\
> 
> How about we add here an
> 
> .if _fw_$(FWSTR)_sha_start - _fw_$(FWSTR)_sha_end
> 	.err
> 	.warnig "sha256sum empty"
> .endif
> 
> As .byte doesn't require an argument, this would ensure breakage to be
> noticed at compile time.

Ok. The .if expression is reversed. Will change to:

	.if _fw_$(FWSTR)_sha_start + 32 - _fw_$(FWSTR)_sha_end
	.error "sha256sum invalid"
	.endif"

This not only checks for an empty sha sum but also for the correct
length.

Sascha

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