linux-kernel - Re: [PATCH v2] drivers/firmware: fix SYSFB depends to prevent build failures

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Date:   Tue, 27 Jul 2021 11:50:56 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Peter Robinson <pbrobinson@...il.com>,
        Mark Brown <broonie@...nel.org>,
        kernel test robot <lkp@...el.com>,
        Borislav Petkov <bp@...e.de>,
        Colin Ian King <colin.king@...onical.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        John Stultz <john.stultz@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v2] drivers/firmware: fix SYSFB depends to prevent build
 failures

On Tue, Jul 27, 2021 at 11:30:15AM +0200, Javier Martinez Canillas wrote:
> The Generic System Framebuffers support is built when the COMPILE_TEST
> option is enabled. But this wrongly assumes that all the architectures
> declare a struct screen_info.
> 
> This is true for most architectures, but at least the following do not:
> arc, m68k, microblaze, openrisc, parisc and s390.
> 
> By attempting to make this compile testeable on all architectures, it
> leads to linking errors as reported by the kernel test robot for parisc:
> 
>   All errors (new ones prefixed by >>):
> 
>      hppa-linux-ld: drivers/firmware/sysfb.o: in function `sysfb_init':
>      (.init.text+0x24): undefined reference to `screen_info'
>   >> hppa-linux-ld: (.init.text+0x28): undefined reference to `screen_info'
> 
> To prevent these errors only allow sysfb to be built on systems that are
> going to need it, which are x86 BIOS and EFI.
> 
> The EFI Kconfig symbol is used instead of (ARM || ARM64 || RISC) because
> some of these architectures only declare a struct screen_info if EFI is
> enabled. And also, because the SYSFB code is only used for EFI on these
> architectures. For !EFI the "simple-framebuffer" device is registered by
> OF when parsing the Device Tree Blob (if a DT node for this was defined).
> 
> Fixes: d391c5827107 ("drivers/firmware: move x86 Generic System Framebuffers support")
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>

Whacked onto drm-next so we're welcome again in linux-next.
-Daniel

> ---
> 
> Changes in v2:
> - Add a Fixes tag to the changelog.
> 
>  drivers/firmware/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index af6719cc576b..897f5f25c64e 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -254,7 +254,7 @@ config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
>  config SYSFB
>  	bool
>  	default y
> -	depends on X86 || ARM || ARM64 || RISCV || COMPILE_TEST
> +	depends on X86 || EFI
>  
>  config SYSFB_SIMPLEFB
>  	bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
> -- 
> 2.31.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch