linux-kernel - Re: [PATCH 1/1] Fonts: font_acorn_8x8: Replace discarded const qualifier

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Date:   Mon, 2 Nov 2020 11:30:34 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Daniel Vetter <daniel.vetter@...ll.ch>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Peilin Ye <yepeilin.cs@...il.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH 1/1] Fonts: font_acorn_8x8: Replace discarded const
 qualifier

On Mon, 02 Nov 2020, Daniel Vetter wrote:

> On Mon, Nov 2, 2020 at 12:09 PM Lee Jones <lee.jones@...aro.org> wrote:
> >
> > On Mon, 02 Nov 2020, Daniel Vetter wrote:
> >
> > > On Fri, Oct 30, 2020 at 7:18 PM Lee Jones <lee.jones@...aro.org> wrote:
> > > >
> > > > Commit 09e5b3fd5672 ("Fonts: Support FONT_EXTRA_WORDS macros for
> > > > built-in fonts") introduced the following error when building
> > > > rpc_defconfig (only this build appears to be affected):
> > > >
> > > >  `acorndata_8x8' referenced in section `.text' of arch/arm/boot/compressed/ll_char_wr.o:
> > > >     defined in discarded section `.data' of arch/arm/boot/compressed/font.o
> > > >  `acorndata_8x8' referenced in section `.data.rel.ro' of arch/arm/boot/compressed/font.o:
> > > >     defined in discarded section `.data' of arch/arm/boot/compressed/font.o
> > > >  make[3]: *** [/scratch/linux/arch/arm/boot/compressed/Makefile:191: arch/arm/boot/compressed/vmlinux] Error 1
> > > >  make[2]: *** [/scratch/linux/arch/arm/boot/Makefile:61: arch/arm/boot/compressed/vmlinux] Error 2
> > > >  make[1]: *** [/scratch/linux/arch/arm/Makefile:317: zImage] Error 2
> > > >
> > > > The .data section is discarded at link time.  Reinstating
> > > > acorndata_8x8 as const ensures it is still available after linking.
> > > >
> > > > Cc: <stable@...r.kernel.org>
> > > > Cc: Russell King <linux@...linux.org.uk>
> > > > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > >
> > > Shouldn't we add the const to all of them, for consistency?
> >
> > The thought did cross my mind.  However, I do not see any further
> > issues which need addressing.  Nor do I have any visibility into what
> > issues may be caused by doing so.  The only thing I know for sure is
> > that this patch fixes the compile error pertained to in the commit
> > message, and I'd like for this fix to be as atomic as possible, as
> > it's designed to be routed through the Stable/LTS trees.
> 
> The trouble is that if we only make one of them const, then it'll take
> so much longer to hit any issues due to code not handling this
> correctly. Being consistent with all fonts sounds like the best
> approach.
> 
> And the original patch that lost the const for the additional data
> also went through cc: stable for all fonts together. So that shouldn't
> be the hold-up.

My plan was to keep the fix as simple as possible.

This is only an issue due to the odd handling of the compressed Arm
image which exclusively references 'acorndata_8x8' and discards it's
.data section.

I am happy to go with the majority on this though.

Does anyone else have an opinion?

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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