From 30bf1c45cac396a3b9637cfe40cb1bba4ebca7a9 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sun, 31 May 2020 14:32:19 +0200
Subject: [PATCH] pc, xen: make PAT support optional (for xen)

---
 sys/src/9/pc/devarch.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/src/9/pc/devarch.c b/sys/src/9/pc/devarch.c
index 595cbcb8b..d637d5aa3 100644
--- a/sys/src/9/pc/devarch.c
+++ b/sys/src/9/pc/devarch.c
@@ -882,12 +882,14 @@ cpuidentify(void)
 			rdmsr(0x01, &mct);
 	}
 
+#ifdef PATWC
 	/* 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);
 	}
+#endif
 
 	if(m->cpuiddx & Mtrr)
 		mtrrsync();