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Message-ID: <182b08ea-04f3-3282-e3c3-9448bab6568a@infradead.org>
Date:   Wed, 2 Aug 2023 07:44:57 -0700
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Subject: Re: [PATCH] powerpc: Use shared font data
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To:     Michael Ellerman <mpe@ellerman.id.au>,
        "Dr. David Alan Gilbert" <linux@treblig.org>
Cc:     npiggin@gmail.com, christophe.leroy@csgroup.eu, sam@ravnborg.org,
        benh@kernel.crashing.org, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org
References: <20230725000141.165985-1-linux@treblig.org>
 <878rb0em3s.fsf@mail.lhotse> <ZMOaz9EqqeaPGokA@gallifrey>
 <871qgl1vs2.fsf@mail.lhotse>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <871qgl1vs2.fsf@mail.lhotse>
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On 8/2/23 05:19, Michael Ellerman wrote:
> "Dr. David Alan Gilbert" <linux@treblig.org> writes:
>> * Michael Ellerman (mpe@ellerman.id.au) wrote:
>>> linux@treblig.org writes:
>>>> From: "Dr. David Alan Gilbert" <linux@treblig.org>
>>>>
>>>> PowerPC has a 'btext' font used for the console which is almost identical
>>>> to the shared font_sun8x16, so use it rather than duplicating the data.
>>>>
>>>> They were actually identical until about a decade ago when
>>>>    commit bcfbeecea11c ("drivers: console: font_: Change a glyph from
>>>>                         "broken bar" to "vertical line"")
>>>>
>>>> which changed the | in the shared font to be a solid
>>>> bar rather than a broken bar.  That's the only difference.
>>>>
>>>> This was originally spotted by PMD which noticed that sparc does
>>>
>>> PMD means "Page Middle Directory" to most Linux folks, I assume that's
>>> not what you meant :)
>>
>> Ah, any good TLA is ripe for reuse:
>>    https://pmd.github.io/pmd/pmd_userdocs_cpd.html
> 
> Thanks.
> 
> Unfortunately this patch causes a warning:
> 
>   WARNING: unmet direct dependencies detected for FONT_SUN8x16
>     Depends on [n]: FONT_SUPPORT [=y] && FRAMEBUFFER_CONSOLE [=y] && (!SPARC && FONTS [=n] || SPARC)
>     Selected by [y]:
>     - BOOTX_TEXT [=y] && PPC_BOOK3S [=y]
> 
> And breaks allmodconfig with:
> 
>   ld: arch/powerpc/kernel/btext.o:(.toc+0x0): undefined reference to `font_sun_8x16'
>   make[3]: *** [../scripts/Makefile.vmlinux:36: vmlinux] Error 1
> 
> I guess the Kconfig logic needs some more work.

Also please see:
  https://lore.kernel.org/all/dd29e5f5-d9f7-0103-e602-b98f26c88fb1@infradead.org/
for a similar problem on UML.

-- 
~Randy