From 25946100e21cf2095bea334e8d7096798561d0b7 Mon Sep 17 00:00:00 2001
From: Vincent Davis Jr <vince@underview.tech>
Date: Wed, 28 Dec 2022 16:28:01 -0600
Subject: [PATCH] gbm/backend: fix gbm compile without dri

Upstream-Status: Backport

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20447
https://gitlab.freedesktop.org/mesa/mesa/-/commit/842ca284650f066e58706741a7d22d67b5088e60

At mesa version 22.2.3 patch wasn't introduced until after.

Commit introduces a fix that allows for gbm to be built with an empty
backend. There are situation especially in a Yocto/OE cross compilation
environment where you want to build with an empty backend. The particular
situation is as such:

The mesa-gl recipe is the preferred provider for virtual/libgbm, virtual/libgl,
virtual/mesa, etc... But the x11 DISTRO_FEATURE in't included this leads to build
errors such as:

| /../../../ld: src/gbm/libgbm.so.1.0.0.p/main_backend.c.o: in function `find_backend':
| backend.c:(.text.find_backend+0xa4): undefined reference to `gbm_dri_backend'
| /../../../ld: src/gbm/libgbm.so.1.0.0.p/main_backend.c.o:(.data.rel.ro.builtin_backends+0x4):
                undefined reference to `gbm_dri_backend'
| collect2: error: ld returned 1 exit status

Issue should be replicable by setting -Ddri3=disabled and -Dgbm=enabled

Add fix to bypasses compilation issue by excluding gbm dri backend. If
HAVE_DRI || HAVE_DRIX not specified.

Acked-by: David Heidelberg <david.heidelberg@collabora.com>
Signed-off-by: Vincent Davis Jr <vince@underview.tech>
---
 src/gbm/main/backend.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/gbm/main/backend.c b/src/gbm/main/backend.c
index 974d0a76a4e..feee0703495 100644
--- a/src/gbm/main/backend.c
+++ b/src/gbm/main/backend.c
@@ -42,7 +42,9 @@
 #define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))
 #define VER_MIN(a, b) ((a) < (b) ? (a) : (b))

+#if defined(HAVE_DRI) || defined(HAVE_DRI2) || defined(HAVE_DRI3)
 extern const struct gbm_backend gbm_dri_backend;
+#endif

 struct gbm_backend_desc {
    const char *name;
@@ -51,7 +53,9 @@ struct gbm_backend_desc {
 };

 static const struct gbm_backend_desc builtin_backends[] = {
+#if defined(HAVE_DRI) || defined(HAVE_DRI2) || defined(HAVE_DRI3)
    { "dri", &gbm_dri_backend },
+#endif
 };

 #define BACKEND_LIB_SUFFIX "_gbm"
--
2.34.1
