Re: port-i386/52266: Double fault early in boot with AMD Am5x86 CPU

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

The following reply was made to PR port-i386/52266; it has been noted by GNATS.

From: "John D. Baker" <jdbaker%mylinuxisp.com@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-i386/52266: Double fault early in boot with AMD Am5x86 CPU
Date: Tue, 11 Jul 2017 17:18:13 -0500 (CDT)

 Looking at the reports so far and the meaning of each of the various
 CPUID_* bits, it looks like:
 
   AMD Am5x86 (Elan SC520):  No MSR, No APIC
   NS Geode:  MSR, No APIC, rdmsr_safe() works
   TM Crusoe:  MSR, No APIC, rdmsr_safe() fails
 
 Are there any CPUs which implement APIC w/o MSR?  If not, then perhaps
 the condition could be made:
 
   if (!(ISSET(cpu_feature[0], APIC) &&
         ISSET(cpu_feature[0], CPUID_MSR)) ||
       rdmsr_safe(MSR_APICBASE, &msr) == EFAULT)
     return false;
 
 to satisfy the above cases?
 
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