Module Name: src
Committed By: rin
Date: Wed Sep 18 22:29:39 UTC 2024
Modified Files:
src/sys/arch/i386/i386: db_interface.c
Log Message:
i386: DDB: Call x86_pause() (`pause` insn) when CPUs are paused
as already done for amd64:
https://mail-index.netbsd.org/source-changes/2023/07/31/msg146423.html
`pause` insn has been introduced to Pentium 4. However, its opcode is
consisted of `nop` (0x90) followed by `rep` prefix (0xf3), and therefore
interpreted as `nop` for older processors. Intel assured this behavior [1].
Also note that we already use `pause` unconditionally for i386.
Briefly tested on QEMU.
[1] Intel, ``AP-949 Using Spin-Loops on Intel Pentium 4 Processor and
Intel Xeon Processor'', Version 2.1, Sec 2.1.1. (2001)
To generate a diff of this commit:
cvs rdiff -u -r1.88 -r1.89 src/sys/arch/i386/i386/db_interface.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/i386/i386/db_interface.c
diff -u src/sys/arch/i386/i386/db_interface.c:1.88 src/sys/arch/i386/i386/db_interface.c:1.89
--- src/sys/arch/i386/i386/db_interface.c:1.88 Wed Oct 26 23:38:07 2022
+++ src/sys/arch/i386/i386/db_interface.c Wed Sep 18 22:29:39 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: db_interface.c,v 1.88 2022/10/26 23:38:07 riastradh Exp $ */
+/* $NetBSD: db_interface.c,v 1.89 2024/09/18 22:29:39 rin Exp $ */
/*
* Mach Operating System
@@ -33,7 +33,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.88 2022/10/26 23:38:07 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_interface.c,v 1.89 2024/09/18 22:29:39 rin Exp $");
#include "opt_ddb.h"
#include "opt_multiprocessor.h"
@@ -369,7 +369,7 @@ ddb_suspend(struct trapframe *frame)
atomic_or_32(&ci->ci_flags, CPUF_PAUSE);
while (ci->ci_flags & CPUF_PAUSE)
- ;
+ x86_pause();
ci->ci_ddb_regs = 0;
tlbflushg();
}
