On Wed, 16 Mar 2011, Jung-uk Kim wrote:
Log:
Rework r219679. Always check CPU class at run-time to make it predictable.
Unfortunately, it pulls in <machine/cputypes.h> but it is small enough and
namespace pollution is minimal, I hope.
Pointed out by: bde
Well, I don't like the namespace pollution, and the old code carefully
avoided it by using the tsc_present global.
Modified: head/sys/i386/include/cpu.h
==============================================================================
--- head/sys/i386/include/cpu.h Wed Mar 16 12:40:58 2011 (r219697)
+++ head/sys/i386/include/cpu.h Wed Mar 16 16:09:08 2011 (r219698)
@@ -39,6 +39,7 @@
/*
* Definitions unique to i386 cpu support.
*/
+#include <machine/cputypes.h>
#include <machine/psl.h>
#include <machine/frame.h>
#include <machine/segments.h>
@@ -69,14 +70,13 @@ void swi_vm(void *);
static __inline uint64_t
get_cyclecount(void)
{
-#if defined(I486_CPU) || defined(KLD_MODULE)
struct bintime bt;
- binuptime(&bt);
- return ((uint64_t)bt.sec << 56 | bt.frac >> 8);
-#else
+ if (cpu_class == CPUCLASS_486) {
+ binuptime(&bt);
+ return ((uint64_t)bt.sec << 56 | bt.frac >> 8);
+ }
return (rdtsc());
-#endif
}
#endif
cpu_class shouldn't be used for anything, and might not be able to
correctly classify whether the CPU has a TSC. The cpu feature for
this should be used. Using it directly with the correct includes
would give considerably more namespace pollution (md_var.h for cpu_feature
and specialreg.h for CPUID_TSC).
Although I said that tsc_present should go, it seems to be the best
thing to use here. Rename it __cpu_feature_TSC to reflect that it is
exactly (cpu_feature & CPUID_TSC) and put underscores in its name so
as to start being even more careful about namespace pollution in cpu.h.
Or redeclare cpu_feature and CPUID_TSC.
Bruce
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