On 07/15/14 08:43, Alan Cox wrote:
On 07/15/2014 09:01, John Baldwin wrote:
On Monday, July 14, 2014 1:53:45 pm Konstantin Belousov wrote:
On Mon, Jul 14, 2014 at 05:42:22PM +0000, Nathan Whitehorn wrote:
Author: nwhitehorn
Date: Mon Jul 14 17:42:22 2014
New Revision: 268624
URL: http://svnweb.freebsd.org/changeset/base/268624
Log:
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.
MFC after: 2 weeks
Modified:
head/sys/dev/vt/hw/efifb/efifb.c
Modified: head/sys/dev/vt/hw/efifb/efifb.c
==============================================================================
--- head/sys/dev/vt/hw/efifb/efifb.c Mon Jul 14 17:16:09 2014
(r268623)
+++ head/sys/dev/vt/hw/efifb/efifb.c Mon Jul 14 17:42:22 2014
(r268624)
@@ -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);
+}
+
Could you use pmap_change_attr() ? This would save some KVA.
I think that is a no-op in this case. pmap_mapdev_attr() on amd64 is already
going to re-use the existing DMAP mapping after doing pmap_change_attr() on
it.
Yes, it automatically uses the direct map:
void *
pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
{
vm_offset_t va, offset;
vm_size_t tmpsize;
/*
* If the specified range of physical addresses fits within the
direct
* map window, use the direct map.
*/
if (pa < dmaplimit && pa + size < dmaplimit) {
va = PHYS_TO_DMAP(pa);
if (!pmap_change_attr(va, size, mode))
return ((void *)va);
Well, I'm glad I didn't fix it earlier :)
-Nathan
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