linux-kernel - Re: Linux 5.1.9 build failure with CONFIG_NOUVEAU_LEGACY_CTX

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Message-ID: <CAKMK7uH_3P3pYkJ9Ua4hOFno5UiQ4p-rdWu9tPO75MxGCbyXSA@mail.gmail.com>
Date:   Tue, 11 Jun 2019 19:33:16 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Sven Joachim <svenjoac@....de>, stable <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dave Airlie <airlied@...hat.com>
Subject: Re: Linux 5.1.9 build failure with CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT=n

On Tue, Jun 11, 2019 at 5:37 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> On Tue, Jun 11, 2019 at 03:56:35PM +0200, Sven Joachim wrote:
> > Commit 1e07d63749 ("drm/nouveau: add kconfig option to turn off nouveau
> > legacy contexts. (v3)") has caused a build failure for me when I
> > actually tried that option (CONFIG_NOUVEAU_LEGACY_CTX_SUPPORT=n):
> >
> > ,----
> > | Kernel: arch/x86/boot/bzImage is ready  (#1)
> > |   Building modules, stage 2.
> > |   MODPOST 290 modules
> > | ERROR: "drm_legacy_mmap" [drivers/gpu/drm/nouveau/nouveau.ko] undefined!
> > | scripts/Makefile.modpost:91: recipe for target '__modpost' failed
> > `----

Calling drm_legacy_mmap is definitely not a great idea. I think either
we need a custom patch to remove that out on older kernels, or maybe
even #ifdef if you want to be super paranoid about breaking stuff ...

> > Upstream does not have that problem, as commit bed2dd8421 ("drm/ttm:
> > Quick-test mmap offset in ttm_bo_mmap()") has removed the use of
> > drm_legacy_mmap from nouveau_ttm.c.  Unfortunately that commit does not
> > apply in 5.1.9.
> >
> > Most likely 4.19.50 and 4.14.125 are also affected, I haven't tested
> > them yet.
>
> They probably are.
>
> Should I just revert this patch in the stable tree, or add some other
> patch (like the one pointed out here, which seems an odd patch for
> stable...)

... or backport the above patch, that should be save to do too. Not
sure what stable folks prefer?
-Daniel

>
> thanks,
>
> greg k-h



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch