On certain newer Intel Atom based motherboards, for instance the

D2500CC which I have, syscons in text-mode fails to show the expected
contents due to write errors into video-memory.

At least one of the causes is that we copy from syscons internal buffer
to the video memory with optimized bcopy(9) which uses >16bit operations.

Until now, 32bit and wider operations have always worked on the video
memory, but since I cannot find a single source which says that this
SHALL work, and since these chipsets/bugs are now out there, this
commit changes syscons to always use 16bit copies on i386 & amd64.

This may be relevevant for PR's:
	166262
	166639
and various other bug reports floating elsewhere on the net, but
I lack hardware to test those.

1 files changed, 10 insertions, 3 deletions

diff --git a/sys/dev/fb/fbreg.h b/sys/dev/fb/fbreg.h
index 623e37c..ac9a6c3 100644
--- a/sys/dev/fb/fbreg.h
+++ b/sys/dev/fb/fbreg.h
@@ -35,9 +35,16 @@
 
 /* some macros */
 #if defined(__amd64__) || defined(__i386__)
-#define bcopy_io(s, d, c)	bcopy((void *)(s), (void *)(d), (c))
-#define bcopy_toio(s, d, c)	bcopy((void *)(s), (void *)(d), (c))
-#define bcopy_fromio(s, d, c)	bcopy((void *)(s), (void *)(d), (c))
+
+static __inline void
+copyw(uint16_t *src, uint16_t *dst, size_t size)
+{
+	while (size--)
+		*dst++ = *src++;
+}
+#define bcopy_io(s, d, c)	copyw((void*)(s), (void*)(d), (c))
+#define bcopy_toio(s, d, c)	copyw((void*)(s), (void*)(d), (c))
+#define bcopy_fromio(s, d, c)	copyw((void*)(s), (void*)(d), (c))
 #define bzero_io(d, c)		bzero((void *)(d), (c))
 #define fill_io(p, d, c)	fill((p), (void *)(d), (c))
 #define fillw_io(p, d, c)	fillw((p), (void *)(d), (c))