From 6dbbb49403c1bf84d6a5b45a80c5fd61868c3957 Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Sat, 15 Feb 2014 09:48:07 +0000
Subject: [PATCH] If opening /dev/pciN read-write fails, try opening it
 read-only.  This allows X to run with machdep.allowaperture=0 on inteldrm(4)
 and radeondrm(4).

ok matthieu@
---
 lib/libpciaccess/src/openbsd_pci.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/libpciaccess/src/openbsd_pci.c b/lib/libpciaccess/src/openbsd_pci.c
index 24759dd8c..a93832cee 100644
--- a/lib/libpciaccess/src/openbsd_pci.c
+++ b/lib/libpciaccess/src/openbsd_pci.c
@@ -599,8 +599,11 @@ pci_system_openbsd_create(void)
 	for (domain = 0; domain < sizeof(pcifd) / sizeof(pcifd[0]); domain++) {
 		snprintf(path, sizeof(path), "/dev/pci%d", domain);
 	        pcifd[domain] = open(path, O_RDWR | O_CLOEXEC);
-		if (pcifd[domain] == -1)
-			break;
+		if (pcifd[domain] == -1) {
+			pcifd[domain] = open(path, O_RDONLY | O_CLOEXEC);
+			if (pcifd[domain] == -1)
+				break;
+		}
 		ndomains++;
 	}