MFC r268624 by nwhitehorn:

  On my Lenovo laptop, the firmware maps the EFI framebuffer with MTRRs
  set to uncacheable. This leads to execrable console performance. Once
  PMAP is up, remap the framebuffer as write-combining. This reduces
  boot time on my laptop by 60% when booting with EFI.

1 files changed, 25 insertions, 3 deletions

diff --git a/sys/dev/vt/hw/efifb/efifb.c b/sys/dev/vt/hw/efifb/efifb.c
index d521cc3..b3347f7 100644
--- a/sys/dev/vt/hw/efifb/efifb.c
+++ b/sys/dev/vt/hw/efifb/efifb.c
@@ -53,6 +53,7 @@ __FBSDID("$FreeBSD$");
 
 static vd_init_t vt_efifb_init;
 static vd_probe_t vt_efifb_probe;
+static void vt_efifb_remap(void *efifb_data);
 
 static struct vt_driver vt_efifb_driver = {
 	.vd_name = "efifb",
@@ -68,6 +69,8 @@ static struct vt_driver vt_efifb_driver = {
 static struct fb_info local_info;
 VT_DRIVER_DECLARE(vt_efifb, vt_efifb_driver);
 
+SYSINIT(efifb_remap, SI_SUB_KMEM, SI_ORDER_ANY, vt_efifb_remap, &local_info);
+
 static int
 vt_efifb_probe(struct vt_device *vd)
 {
@@ -133,9 +136,9 @@ vt_efifb_init(struct vt_device *vd)
 	info->fb_size = info->fb_height * info->fb_stride;
 	info->fb_pbase = efifb->fb_addr;
 	/*
-	 * We could use pmap_mapdev here except that the kernel pmap
-	 * hasn't been created yet and hence any attempt to lock it will
-	 * fail.
+	 * Use the direct map as a crutch until pmap is available. Once pmap
+	 * is online, the framebuffer will be remapped by vt_efifb_remap()
+	 * using pmap_mapdev_attr().
 	 */
 	info->fb_vbase = PHYS_TO_DMAP(efifb->fb_addr);
 
@@ -163,3 +166,22 @@ vt_efifb_init(struct vt_device *vd)
 
 	return (CN_INTERNAL);
 }
+
+static void
+vt_efifb_remap(void *xinfo)
+{
+	struct fb_info *info = xinfo;
+
+	if (info->fb_pbase == 0)
+		return;
+
+	/*
+	 * Remap as write-combining. This massively improves performance and
+	 * happens very early in kernel initialization, when everything is
+	 * still single-threaded and interrupts are off, so replacing the
+	 * mapping address is safe.
+	 */
+	info->fb_vbase = (intptr_t)pmap_mapdev_attr(info->fb_pbase,
+	    info->fb_size, VM_MEMATTR_WRITE_COMBINING);
+}
+