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;Check if CPU is a Cyrix with CPUID disabled.
;_______________________________________________________________________________

   clr ax
   sahf
   mov  ax,5
   mov  bx,2
   div  bl
   lahf
   cmp  ah,2         ;Is it Cyrix?
   jne .is486         ; no, must be 80486

;Cyrix Detected - Try To Enable CPUID
;_______________________________________________________________________________

;Preset CPU vendor string to 'CyrixInstead' in case CPUID not supported

   mov dword [gs:edi+CPUdataStruct.vendorString],'Cyri'
   mov dword [gs:edi+CPUdataStruct.vendorString+4],'xIns'
   mov dword [gs:edi+CPUdataStruct.vendorString+8],'tead'

;Get processor ID

   pushfd            ;Save eflags
   cli            ;Disable interrupts
   mov al,0xFE
   out 0x22,al         ;Address = device ID register 0
   clr ebx
   in al,0x23         ;al = device ID register 0
   mov bh,al         ;bh = device ID register 0
   mov al,0xFF
   out 0x22,al         ;Address = device ID register 1
   in al,0x23         ;al = device ID register 1
   popfd            ;Restore original eflags (and interrupts)

   mov bl,al         ;bh = device ID register 1
   cmp bh,0x20         ;Is it a 486?
   jb .oldCyrix         ; yes, no CPUID anyway

;Try to enable CPUID

   pushfd            ;Save eflags
   cli            ;Disable interrupts
   mov al,0xC3
   out 0x22,al         ;Address = config register 3
   in al,0x23         ;al = config register 3
   mov ch,0x0F         ;ch = config register 3 mask
   mov cl,al         ;cl = original config register 3 contents
   and ch,al
   or ch,0x10
   mov al,0xC3
   out 0x22,al         ;Address = config register 3
   mov al,ch
   out 0x23,al         ;Set new config register 3 (enable config access)

   mov al,0xE8
   out 0x22,al         ;Address = config register 4
   mov ch,0x80         ;ch = CPUID enable bit
   in al,0x23         ;al = current config register 4 contents
   or ch,al         ;ch = config register 4 with CPUID enable bit
   mov al,0xE8
   out 0x22,al         ;Address = config register 4
   mov al,ch         ;al = config register 4 with CPUID enable bit
   out 0x23,al         ;Set CPUID enabled bit

   mov al,bh         ;al = device ID register 0
   and al,0xF0
   cmp al,0x30         ;Is it an early 6x86?
   jne .not6x86         ; no

   mov al,0xE9
   out 0x22,al         ;Address = config register 5
   mov ch,0xFD         ;ch = mask
   in al,0x23         ;al = config register 5
   and ch,al         ;ch = fixed config register 5
   mov al,0xE9
   out 0x22,al         ;Address = config register 5
   mov al,ch         ;al = fixed config register 5
   out 0x23,al         ;Set new config register 5 (attempt to fix CPU bug)
.not6x86:
   mov al,0xC3
   out 0x22,al         ;Address = config register 3
   mov al,cl
   out 0x23,al         ;Restore old config register 3 (disable config access)

;Recheck CPUID presence

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case 0x69727943: /* Cyrix Magic Code */
do_cyrix();
break;

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int do_cyrix(void)
{
        printf("Cyrix-specific functions:\n");
        unsigned long eax, unused;
        int model, family, stepping, reserved;
        cpuid(1, eax, unused, unused, unused);
        model = (eax >> 4) & 0xf;
        family = (eax >> 8) & 0xf;
        stepping = eax & 0xf;
        reserved = eax >> 12;
        printf("Family: %d Model: %d [", family, model);
        switch(family)
        {
                case 4:
                switch(model)
                {
                        case 4:
                        printf("MediaGX");
                        break;
                }
                break;
                case 5:
                switch(model)
                {
                        case 2:
                        printf("6x86");
                        break;
                        case 4:
                        printf("BXm");
                        break;
                }
                break;
                case 6:
                switch(model)
                {
                        case 0:
                        printf("6x86/MX");
                        break;
                }
                break;
        }
        printf("Stepping %d\n", stepping);
        printf("Reserved %d\n", reserved);
}

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#include <stdio.h>
#define cpuid(in, a, b, c, d) asm("cpuid": "=a" (a), "=b" (b), "=c" (c), "=d" (d) : "a" (in));

int main(void)
{
        unsigned int ebx, unused;
        cpuid(0, unused, ebx, unused, unused);
        printf("0x%x\n", ebx);
        return 0;
}

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#include <stdio.h>
#define cpuid(in,a,b,c,d) asm("cpuid": "=a" (a), "=b" (b), "=c" (c), "=d" (d) : "a" (in));

int main(void)
{
	unsigned long unused, eax;
	cpuid(0x80000008, eax, unused, unused, unused);
	printf("Maximum Linear Address: %ld\n", (eax >> 8) & 0xff);
	printf("Maximum Physical Address: %ld\n", eax & 0xff);
}

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patch -p0 -i cpudet-better_intel_brand_detection.patch cpudet-clean.c