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pc: check Sse (bit 25) in cpuiddx before enabling fxsr in cr4 (fixes crash on the pentium II)

--- a/sys/src/9/pc/devarch.c

+++ b/sys/src/9/pc/devarch.c

@@ -864,7 +864,7 @@

 	if(m->cpuiddx & Mtrr)

 		mtrrsync();

-	if(m->cpuiddx & Fxsr){			/* have sse fp? */

+	if((m->cpuiddx & (Sse|Fxsr)) == (Sse|Fxsr)){			/* have sse fp? */

 		fpsave = fpssesave;

 		fprestore = fpsserestore;

 		putcr4(getcr4() | CR4Osfxsr|CR4Oxmmex);