linux-kernel - Re: build failure in linux-next: offb missing fb helpers

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Date:   Sat, 19 Nov 2022 22:27:04 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Michal Suchánek <msuchanek@...e.de>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-fbdev@...r.kernel.org, linux-kbuild@...r.kernel.org
Subject: Re: build failure in linux-next: offb missing fb helpers

On Sat, Nov 19, 2022 at 3:20 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>
> Hi--
>
> [adding Masahiro-san]
>
>
> On 11/18/22 07:03, Michal Suchánek wrote:
> > Hello,
> >
> > I am seeing these errors:
> >
> > [ 3825s]   AR      built-in.a
> > [ 3827s]   AR      vmlinux.a
> > [ 3835s]   LD      vmlinux.o
> > [ 3835s]   OBJCOPY modules.builtin.modinfo
> > [ 3835s]   GEN     modules.builtin
> > [ 3835s]   GEN     .vmlinux.objs
> > [ 3848s]   MODPOST Module.symvers
> > [ 3848s]   CC      .vmlinux.export.o
> > [ 3849s]   UPD     include/generated/utsversion.h
> > [ 3849s]   CC      init/version-timestamp.o
> > [ 3849s]   LD      .tmp_vmlinux.btf
> > [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x58): undefined
> > reference to `cfb_fillrect'
> > [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x60): undefined
> > reference to `cfb_copyarea'
> > [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x68): undefined
> > reference to `cfb_imageblit'
> >
> > cfb_fillrect is provided by drivers/video/fbdev/core/cfbfillrect.c
> >
> > It is compiled when CONFIG_FB_CFB_FILLRECT
> > drivers/video/fbdev/core/Makefile:obj-$(CONFIG_FB_CFB_FILLRECT)  += cfbfillrect.o
> >
> > drivers/video/fbdev/Makefile:obj-$(CONFIG_FB_OF)               += offb.o
> > is compiled when CONFIG_FB_OF
> >
> > It selects CONFIG_FB_CFB_FILLRECT
> > config FB_OF
> >         bool "Open Firmware frame buffer device support"
> >         depends on (FB = y) && PPC && (!PPC_PSERIES || PCI)
> >         select APERTURE_HELPERS
> >         select FB_CFB_FILLRECT
> >         select FB_CFB_COPYAREA
> >         select FB_CFB_IMAGEBLIT
> >         select FB_MACMODES
> >
> > The config has FB_OF built-in and FB_CFB_FILLRECT modular
> > config/ppc64le/vanilla:CONFIG_FB_CFB_FILLRECT=m
> > config/ppc64le/vanilla:CONFIG_FB_CFB_COPYAREA=m
> > config/ppc64le/vanilla:CONFIG_FB_CFB_IMAGEBLIT=m
> > config/ppc64le/vanilla:CONFIG_FB_OF=y
> >
> > It only depends on FB which mut be built-in for FB_OF
> > config FB_CFB_FILLRECT
> >         tristate
> >         depends on FB
> >
> > Is select in kconfig broken?
> >
> > Attachnig the config in question.
>
> The symbol info from xconfig says:
>
> Symbol: FB_CFB_FILLRECT [=m]
> Type : tristate
> Defined at drivers/video/fbdev/Kconfig:69
> Depends on: HAS_IOMEM [=y] && FB [=y]
> Selected by [m]:
> [deleted]
> - FB_OF [=y] && HAS_IOMEM [=y] && FB [=y]=y && PPC [=y] && (!PPC_PSERIES [=y] || PCI [=y]) && !DRM_OFDRM [=m]
>
> I don't see why the 'select' from (bool) FB_OF would leave FB_CFB_FILLRECT (and the others)
> as =m instead of =y.
>
> Hopefully Masahiro can shed some light on this.
>
> --
> ~Randy


The reason is shown in your paste of help message:

"&& !DRM_OFDRM [=m]" downgrades it to "selected by m"

To aid this particular case, the following will select
FB_CFB_FILLRECT=y.




diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index 66f36b69e8f3..2bcf8627819f 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -458,7 +458,7 @@ config FB_ATARI
 config FB_OF
        bool "Open Firmware frame buffer device support"
        depends on (FB = y) && PPC && (!PPC_PSERIES || PCI)
-       depends on !DRM_OFDRM
+       depends on DRM_OFDRM != y
        select APERTURE_HELPERS
        select FB_CFB_FILLRECT
        select FB_CFB_COPYAREA




Or, perhaps "depends on DRM_OFDRM = n"
I do not know the intention of this dependency.

Recommendation is to use "depends on" instead of "select" though.



BTW, this is similar to what you asked before.

https://lore.kernel.org/linux-kbuild/e1a6228d-1341-6264-d97a-e2bd52a65c82@infradead.org/


I tried to fix it in the past, but the issue was not as shallow as I
had expected.
I did not get around to revisiting this topic.

https://patchwork.kernel.org/project/linux-kbuild/patch/1543216969-2227-1-git-send-email-yamada.masahiro@socionext.com/










--
Best Regards
Masahiro Yamada