Bochs/bochs/patches/patch.tsc-bryce
Bryce Denney a2d70c9953 - separate Zwane's patch and my patch so they can be more easily compared.
Now patch.tsc-zwane is back to exactly what Zwane sent to me, and
  patch.tsc-bryce has my modified version.
2002-09-27 23:17:04 +00:00

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----------------------------------------------------------------------
Patch name: patch.tsc-zwane
Author: Zwane Mwaikambo <zwane@linuxpower.ca>, Bryce Denney <bryce@tlw.com>
Date: Tue, 24 Sep 2002 19:44:51 -0400 (EDT)
Detailed description:
Zwane's original comments:
This patch will seperate the TSC from the other timers, this helps a lot
in speeding up SMP boot and allows TSC synch to be possible. Seperation is
definitely necessary for writing to the TSC (e.g. via WRMSR)
Bryce's comments:
I took Zwane's patch and modified it so that
1) the TSCs for each cpu increment with ticks, not with ticks/COUNTER_INTERVAL
2) updating the TSC values do not cost any time per instruction. The
TSC value for each CPU is computed only when it is needed.
Patch was created with:
cvs diff -u
Apply patch to what version:
cvs checked out on DATE, release version VER
Instructions:
To patch, go to main bochs directory.
Type "patch -p0 < THIS_PATCH_FILE".
----------------------------------------------------------------------
Index: cpu/cpu.h
===================================================================
RCS file: /cvsroot/bochs/bochs/cpu/cpu.h,v
retrieving revision 1.82
diff -u -r1.82 cpu.h
--- cpu/cpu.h 26 Sep 2002 21:32:25 -0000 1.82
+++ cpu/cpu.h 27 Sep 2002 03:17:41 -0000
@@ -585,6 +585,13 @@
typedef struct {
Bit64u apicbase;
+ // TSC: Time Stamp Counter
+ // Instead of storing a counter and incrementing it every instruction, we
+ // remember the time in ticks that it was reset to zero. With a little
+ // algebra, we can also support setting it to something other than zero.
+ // Don't read this directly; use get_tsc and set_tsc to access the TSC.
+ Bit64u tsc_last_reset_time;
+
#if BX_SUPPORT_X86_64
// x86-64 EFER bits
Boolean sce;
@@ -1390,6 +1397,10 @@
#if BX_CPU_LEVEL >= 5
bx_regs_msr_t msr;
+
+ // these methods are implemented in proc_ctrl.cc
+ Bit64u get_TSC ();
+ void set_TSC (Bit64u newval);
#endif
i387_t the_i387;
Index: cpu/init.cc
===================================================================
RCS file: /cvsroot/bochs/bochs/cpu/init.cc,v
retrieving revision 1.32
diff -u -r1.32 init.cc
--- cpu/init.cc 22 Sep 2002 18:22:24 -0000 1.32
+++ cpu/init.cc 27 Sep 2002 03:17:42 -0000
@@ -818,6 +818,9 @@
/* initialise MSR registers to defaults */
#if BX_CPU_LEVEL >= 5
+ // initialize tsc to zero
+ BX_CPU_THIS_PTR set_TSC (0);
+
/* APIC Address, APIC enabled and BSP is default, we'll fill in the rest later */
BX_CPU_THIS_PTR msr.apicbase = (APIC_BASE_ADDR << 12) + 0x900;
#if BX_SUPPORT_X86_64
Index: cpu/proc_ctrl.cc
===================================================================
RCS file: /cvsroot/bochs/bochs/cpu/proc_ctrl.cc,v
retrieving revision 1.51
diff -u -r1.51 proc_ctrl.cc
--- cpu/proc_ctrl.cc 25 Sep 2002 14:09:08 -0000 1.51
+++ cpu/proc_ctrl.cc 27 Sep 2002 03:17:44 -0000
@@ -1644,6 +1644,20 @@
#endif
}
+
+
+Bit64u BX_CPU_C::get_TSC () {
+ return bx_pc_system.time_ticks() - BX_CPU_THIS_PTR msr.tsc_last_reset_time;
+}
+
+void BX_CPU_C::set_TSC (Bit64u newval) {
+ // compute the correct setting of tsc_last_reset_time so that a get_TSC()
+ // will return newval.
+ BX_CPU_THIS_PTR msr.tsc_last_reset_time = bx_pc_system.time_ticks() - newval;
+ // verify
+ BX_ASSERT (get_TSC() == newval);
+}
+
void
BX_CPU_C::RDTSC(bxInstruction_c *i)
{
@@ -1652,9 +1666,10 @@
Boolean cpl = CPL;
if ((tsd==0) || (tsd==1 && cpl==0)) {
// return ticks
- Bit64u ticks = bx_pc_system.time_ticks ();
+ Bit64u ticks = BX_CPU_THIS_PTR get_TSC ();
RAX = (Bit32u) (ticks & 0xffffffff);
- RDX = (Bit32u) ((ticks >> 32) & 0xffffffff);
+ RDX = (Bit32u) (ticks >> 32);
+
//BX_INFO(("RDTSC: returning EDX:EAX = %08x:%08x", EDX, EAX));
} else {
// not allowed to use RDTSC!
@@ -1812,7 +1827,6 @@
/* The following registers are defined for Pentium only */
case BX_MSR_P5_MC_ADDR:
case BX_MSR_MC_TYPE:
- case BX_MSR_TSC:
case BX_MSR_CESR:
/* TODO */
return;
@@ -1820,7 +1834,6 @@
/* These are noops on i686... */
case BX_MSR_P5_MC_ADDR:
case BX_MSR_MC_TYPE:
- case BX_MSR_TSC:
/* do nothing */
return;
@@ -1830,6 +1843,12 @@
case BX_MSR_CTR1:
goto do_exception;
#endif /* BX_CPU_LEVEL == 5 */
+
+ case BX_MSR_TSC:
+ /* we ignore the high 32bits */
+ BX_CPU_THIS_PTR set_TSC (RAX & 0xffffffff);
+ BX_INFO(("WRMSR: wrote %08x:%08x to MSR_TSC\n", 0, EAX));
+ return;
/* MSR_APICBASE
0:7 Reserved