pc, pc64: do page attribute table (PAT) init early in cpuidentify()

the page attribute table was initialized in mmuinit(), which is
too late for bootscreen(). So now we check for PAT support and
insert the write-combine entry early in cpuidentify().

this might have been the cause of some slow EFI framebuffers on
machines with overlapping or insufficient MTRR entries.

5 files changed, 13 insertions, 25 deletions

diff --git a/sys/src/9/pc/devarch.c b/sys/src/9/pc/devarch.c
index 2da6f5d55..595cbcb8b 100644
--- a/sys/src/9/pc/devarch.c
+++ b/sys/src/9/pc/devarch.c
@@ -749,7 +749,7 @@ cpuidentify(void)
 	X86type *t, *tab;
 	uintptr cr4;
 	ulong regs[4];
-	vlong mca, mct;
+	vlong mca, mct, pat;
 
 	cpuid(Highstdfunc, regs);
 	memmove(m->cpuidid,   &regs[1], BY2WD);	/* bx */
@@ -882,6 +882,13 @@ cpuidentify(void)
 			rdmsr(0x01, &mct);
 	}
 
+	/* IA32_PAT write combining */
+	if((m->cpuiddx & Pat) != 0 && rdmsr(0x277, &pat) != -1){
+		pat &= ~(255LL<<(PATWC*8));
+		pat |= 1LL<<(PATWC*8);	/* WC */
+		wrmsr(0x277, pat);
+	}
+
 	if(m->cpuiddx & Mtrr)
 		mtrrsync();
 
diff --git a/sys/src/9/pc/mem.h b/sys/src/9/pc/mem.h
index 56649e305..ef646db7d 100644
--- a/sys/src/9/pc/mem.h
+++ b/sys/src/9/pc/mem.h
@@ -173,3 +173,5 @@
 
 #define	getpgcolor(a)	0
 
+/* PAT entry used for write combining */
+#define PATWC	7
diff --git a/sys/src/9/pc/mmu.c b/sys/src/9/pc/mmu.c
index c0b13674a..614339295 100644
--- a/sys/src/9/pc/mmu.c
+++ b/sys/src/9/pc/mmu.c
@@ -66,11 +66,6 @@ static void memglobal(void);
 #define	VPTX(va)		(((ulong)(va))>>12)
 #define	vpd (vpt+VPTX(VPT))
 
-enum {
-	/* PAT entry used for write combining */
-	PATWC	= 7,
-};
-
 void
 mmuinit(void)
 {
@@ -125,14 +120,6 @@ mmuinit(void)
 
 	taskswitch(PADDR(m->pdb),  (ulong)m + BY2PG);
 	ltr(TSSSEL);
-
-	/* IA32_PAT write combining */
-	if((MACHP(0)->cpuiddx & Pat) != 0
-	&& rdmsr(0x277, &v) != -1){
-		v &= ~(255LL<<(PATWC*8));
-		v |= 1LL<<(PATWC*8);	/* WC */
-		wrmsr(0x277, v);
-	}
 }
 
 /* 
diff --git a/sys/src/9/pc64/mem.h b/sys/src/9/pc64/mem.h
index 3a9bf9a1a..c6f9bba70 100644
--- a/sys/src/9/pc64/mem.h
+++ b/sys/src/9/pc64/mem.h
@@ -176,5 +176,8 @@
 
 #define	getpgcolor(a)	0
 
+/* PAT entry used for write combining */
+#define PATWC	7
+
 #define RMACH		R15			/* m-> */
 #define RUSER		R14			/* up-> */
diff --git a/sys/src/9/pc64/mmu.c b/sys/src/9/pc64/mmu.c
index f7c8bb7e5..970d0f262 100644
--- a/sys/src/9/pc64/mmu.c
+++ b/sys/src/9/pc64/mmu.c
@@ -38,9 +38,6 @@ enum {
 	PDE	= 0,
 
 	MAPBITS	= 8*sizeof(m->mmumap[0]),
-
-	/* PAT entry used for write combining */
-	PATWC	= 7,
 };
 
 static void
@@ -133,14 +130,6 @@ mmuinit(void)
 	wrmsr(Star, ((uvlong)UE32SEL << 48) | ((uvlong)KESEL << 32));
 	wrmsr(Lstar, (uvlong)syscallentry);
 	wrmsr(Sfmask, 0x200);
-
-	/* IA32_PAT write combining */
-	if((MACHP(0)->cpuiddx & Pat) != 0
-	&& rdmsr(0x277, &v) != -1){
-		v &= ~(255LL<<(PATWC*8));
-		v |= 1LL<<(PATWC*8);	/* WC */
-		wrmsr(0x277, v);
-	}
 }
 
 /*