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pc, pc64: cleanup cpuidentify() and some comments

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This commit is contained in:
cinap_lenrek 2020-12-08 16:58:41 +01:00
parent b2ffb6ccc5
commit 8efbd243e1
1 changed files with 19 additions and 14 deletions
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33
sys/src/9/pc/devarch.c
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@ -491,16 +491,19 @@ cpuidprint(void)
* (if so turn it on)
* - whether or not it supports the page global flag
* (if so turn it on)
* - detect PAT feature and add write-combining entry
* - detect MTRR support and synchronize state with cpu0
* - detect NX support and enable it for AMD64
* - detect watchpoint support
* - detect FPU features and enable the FPU
*/
int
cpuidentify(void)
{
char *p;
int family, model, nomce;
int family, model;
X86type *t, *tab;
uintptr cr4;
ulong regs[4];
vlong mca, mct, pat;
uintptr cr4;
cpuid(Highstdfunc, 0, regs);
memmove(m->cpuidid, &regs[1], BY2WD); /* bx */
@ -567,14 +570,13 @@ cpuidentify(void)
* If machine check was enabled clear out any lingering status.
*/
if(m->cpuiddx & (Pge|Mce|Pse)){
vlong mca, mct;
cr4 = getcr4();
if(m->cpuiddx & Pse)
cr4 |= 0x10; /* page size extensions */
if(p = getconf("*nomce"))
nomce = strtoul(p, 0, 0);
else
nomce = 0;
if((m->cpuiddx & Mce) != 0 && !nomce){
if((m->cpuiddx & Mce) != 0 && getconf("*nomce") == nil){
if((m->cpuiddx & Mca) != 0){
vlong cap;
int bank;
@ -626,7 +628,6 @@ cpuidentify(void)
cr4 |= 0x80; /* page global enable bit */
m->havepge = 1;
}
putcr4(cr4);
if((m->cpuiddx & (Mca|Mce)) == Mce)
@ -635,10 +636,14 @@ cpuidentify(void)
#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);
if((m->cpuiddx & Pat) != 0){
vlong pat;
if(rdmsr(0x277, &pat) != -1){
pat &= ~(255LL<<(PATWC*8));
pat |= 1LL<<(PATWC*8); /* WC */
wrmsr(0x277, pat);
}
}
#endif