git: 9front

Download patch

ref: 283b0de48917d81ceab639a2c26e9349f2b05f22
parent: 8a2412e1e779afa67331bd88f585aab5b88ce5fd
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Tue Oct 1 20:58:46 EDT 2019 

vgai81x: use vmap() for uncached access to cursor data instead of manipulating kernel page table

on 386, the kernel memory region is mapped using huge 4MB pages
(when supported by the cpu). so the uncached pte manipulation
does not work to map the cursor data with uncached attribute.

instead, we allocate a memory page using newpage() and map
it globally using vmap(), which maps it uncached.


--- a/sys/src/9/pc/vgai81x.c
+++ b/sys/src/9/pc/vgai81x.c
@@ -56,7 +56,7 @@
 	Pcidev *p;
 	int size;
 	Mach *mach0;
-	ulong *pgtbl, *rp, cursor, *pte, fbuf, fbend;
+	ulong *pgtbl, *rp, fbuf, fbend;
 	
 	if(scr->mmio)
 		return;
@@ -90,18 +90,7 @@
 		fbuf += BY2PG;
 	}
 
-	/*
-	 * allocate space for the cursor data in system memory.
-	 * must be uncached.
-	 */
-	cursor = (ulong)xspanalloc(BY2PG, BY2PG, 0);
-	mach0 = MACHP(0);
-	pte = mmuwalk(mach0->pdb, cursor, 2, 0);
-	if(pte == nil)
-		panic("i81x cursor mmuwalk");
-	*pte |= PTEUNCACHED;
-	scr->storage = cursor;
-
+	scr->storage = 0;
 	scr->blank = i81xblank;
 }
 
@@ -123,7 +112,7 @@
 	uchar *p;
 	CursorI81x *hwcurs;
 
-	if(scr->mmio == 0)
+	if(scr->mmio == 0 || scr->storage == 0)
 		return;
 	hwcurs = (void*)((uchar*)scr->mmio+hwCur);
 
@@ -192,17 +181,26 @@
 {
 	int i;
 	uchar *p;
-	CursorI81x *hwcurs;
 
 	i81xenable(scr);
 	if(scr->mmio == 0)
 		return;
-	hwcurs = (void*)((uchar*)scr->mmio+hwCur);
 
+	if(scr->storage == 0){
+		CursorI81x *hwcurs;
+		Page *pg = newpage(0, nil, 0);
+		scr->storage = (uintptr)vmap(pg->pa, BY2PG);
+		if(scr->storage == 0){
+			putpage(pg);
+			return;
+		}
+		hwcurs = (void*)((uchar*)scr->mmio+hwCur);
+		hwcurs->base = pg->pa;
+	}
+
 	/*
 	 * Initialise the 32x32 cursor to be transparent in 2bpp mode.
 	 */
-	hwcurs->base = PADDR(scr->storage);
 	p = (uchar*)scr->storage;
 	for(i = 0; i < 32/2; i++) {
 		memset(p, 0xff, 8);
@@ -209,6 +207,7 @@
 		memset(p+8, 0, 8);
 		p += 16;
 	}
+
 	/*
 	 * Load, locate and enable the 32x32 cursor in 2bpp mode.
 	 */
-- 
⑨