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Date:   Tue, 8 Aug 2023 23:02:22 +0000
From:   "Dr. David Alan Gilbert" <linux@treblig.org>
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu,
        sam@ravnborg.org, benh@kernel.crashing.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] powerpc: Use shared font data
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References: <20230807010721.799613-1-linux@treblig.org>
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* Randy Dunlap (rdunlap@infradead.org) wrote:
> 
> 
> On 8/8/23 10:28, Dr. David Alan Gilbert wrote:
> > * Randy Dunlap (rdunlap@infradead.org) wrote:
> >> Hi--
> >>
> >> On 8/6/23 18:07, linux@treblig.org wrote:
> >>> 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
> >>> the same thing with the same data, and they also share a bunch
> >>> of functions to manipulate the data.  I've previously posted a near
> >>> identical patch for sparc.
> >>>
> >>> One difference I notice in PowerPC is that there are a bunch of compile
> >>> options for the .c files for the early code to avoid a bunch of security
> >>> compilation features;  it's not clear to me if this is a problem for
> >>> this font data.
> >>>
> >>> Tested very lightly with a boot without FS in qemu.
> >>>
> >>> v2
> >>>   Added 'select FONT_SUPPORT' (to stop modconfig causing the font to be
> >>>    linked into a module rather than the main kernel)
> >>>   Added 'select FONTS' to satisfy requirements in lib/fonts
> >>>
> >>> Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
> >>> ---
> >>>  arch/powerpc/Kconfig.debug  |   3 +
> >>>  arch/powerpc/kernel/btext.c | 360 +-----------------------------------
> >>>  2 files changed, 9 insertions(+), 354 deletions(-)
> >>>
> >>> diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
> >>> index 2a54fadbeaf51..521c4baf30e88 100644
> >>> --- a/arch/powerpc/Kconfig.debug
> >>> +++ b/arch/powerpc/Kconfig.debug
> >>> @@ -147,6 +147,9 @@ config BDI_SWITCH
> >>>  config BOOTX_TEXT
> >>>  	bool "Support for early boot text console (BootX or OpenFirmware only)"
> >>>  	depends on PPC_BOOK3S
> >>> +	select FONT_SUN8x16
> >>> +	select FONT_SUPPORT
> >>> +	select FONTS
> >>>  	help
> >>>  	  Say Y here to see progress messages from the boot firmware in text
> >>>  	  mode. Requires either BootX or Open Firmware.
> >>
> >> kconfig tells me:
> >>
> >> WARNING: unmet direct dependencies detected for FONTS
> >>   Depends on [n]: FONT_SUPPORT [=y] && (FRAMEBUFFER_CONSOLE [=n] || STI_CONSOLE [=n])
> >>   Selected by [y]:
> >>   - BOOTX_TEXT [=y] && PPC_BOOK3S [=y]
> >>
> >> WARNING: unmet direct dependencies detected for FONT_SUN8x16
> >>   Depends on [n]: FONT_SUPPORT [=y] && FRAMEBUFFER_CONSOLE [=n] && (!SPARC && FONTS [=y] || SPARC)
> >>   Selected by [y]:
> >>   - BOOTX_TEXT [=y] && PPC_BOOK3S [=y]
> >>
> >> because FONTS depends on FRAMEBUFFER_CONSOLE || STI_CONSOLE and neither of those is set.
> > 
> > I'm not getting the warnings in the v2, with a few configs; what command
> > are using?
> > 
> 
> My 'make' build target is either pp32_randconfig or ppc64_randconfig.
> I see kconfig warnings in > 50% of the randconfigs. (small sample size,
> around 20)

Thanks, that triggers it for me; I'll have a discussion with it....

Dave

> 
> > I'm tempted to change the FONT_SUN8x16 dependency line to have
> > SPARC||BOOTX_TEXT or SPARC||POWERPC  and drop the 'select FONTS' I
> > added.
> > 
> > Dave
> > 
> >>
> >> -- 
> >> ~Randy
> 
> -- 
> ~Randy
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/