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[PATCH] x86/APIC: drop 32-bit days remnants


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 17 Jan 2022 11:33:10 +0100
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  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Mon, 17 Jan 2022 10:33:25 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Mercury and Neptune were Pentium chipsets - no need to work around their
errata, even more so that the workaround looks fragile.

Also ditch a Pentium-related and stale part of a comment.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -1042,11 +1042,6 @@ static void __init wait_8254_wraparound(
     do {
         prev_count = curr_count;
         curr_count = get_8254_timer_count();
-
-        /* workaround for broken Mercury/Neptune */
-        if (prev_count >= curr_count + 0x100)
-            curr_count = get_8254_timer_count();
-        
     } while (prev_count >= curr_count);
 }
 
@@ -1056,9 +1051,6 @@ static void __init wait_8254_wraparound(
  * this function twice on the boot CPU, once with a bogus timeout
  * value, second time for real. The other (noncalibrating) CPUs
  * call this function only once, with the real, calibrated value.
- *
- * We do reads before writes even if unnecessary, to get around the
- * P5 APIC double write bug.
  */
 
 #define APIC_DIVISOR 1




 


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