ValidationKit

Timestamp:

Apr 23, 2016 1:01:49 AM (9 years ago)

Author:

vboxsync

Message:

bs3kit: Removed unnecessary (for bs3kit) 286 detection code.

File:

trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-mode-CpuDetect.asm

-              r60672
+              r60673
         ; The 286 stores 0xff in the high byte of the SIDT and SGDT base
         ; address (since it only did 24-bit addressing and the top 8-bit was
+        ; reserved for the 386).  This test prays for no NMIs while we
+        ; potentially modify the SIDT base (not an issue for bs3kit).
+        ;
+        cli
+        mov     ax, 00ffh
+        ; reserved for the 386).  ASSUMES low IDT (which is the case for BS3Kit).
+        ;
         sidt    [xBP - xCB*4 - 20h]
+        xchg    ah, [xBP - xCB*4 - 20h + 2 + 3]
+        cmp     ah, al
+        cmp     [xBP - xCB*4 - 20h + 2 + 3], 0ffh
         jne     .386plus
+%if 1
+        lidt    [xBP - xCB*4 - 20h]
+        sidt    [xBP - xCB*4 - 20h]
+        xchg    ah, [xBP - xCB*4 - 20h + 2 + 3]
+        lidt    [xBP - xCB*4 - 20h]
+        cmp     ah, al
+        jne     .386plus
+%else
+ %if 0
+        ;
         ; Detect 80286 by checking whether the IOPL and NT bits of EFLAGS can be
 …
         ; by a flaky POPF implementation, we assume this isn't the case in our
         ; execution environment.
 %endif
+ %endif
 .is_286:
         mov     ax, BS3CPU_80286

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