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Groups > linux.kernel > #1362019

[PATCH 1/2] Disable UV BAU by default

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For several years, the common practice has been to boot UVs with the
"nobau" parameter on the command line, to disable the BAU.  We've
decided that it makes more sense to just disable the BAU by default in
the kernel, and provide the option to turn it on, if desired.

Signed-off-by: Alex Thorlton <athorlton@sgi.com>
Reviewed-by: Hedi Berriche <hedi@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
---
 arch/x86/platform/uv/tlb_uv.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 3b6ec42..a5609a3 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -37,7 +37,7 @@ static int timeout_base_ns[] = {
 };
 
 static int timeout_us;
-static int nobau;
+static int nobau = 1;
 static int nobau_perm;
 static cycles_t congested_cycles;
 
@@ -106,13 +106,22 @@ static char *stat_description[] = {
 	"enable:   number times use of the BAU was re-enabled"
 };
 
-static int __init
-setup_nobau(char *arg)
+static int __init setup_bau(char *arg)
 {
-	nobau = 1;
+	if (!arg)
+		return -EINVAL;
+
+	if (!strncmp(arg, "on", 2)) {
+		nobau = 0;
+		pr_info("UV BAU Enabled\n");
+	} else if (!strncmp(arg, "off", 3)) {
+		nobau = 1;
+		pr_info("UV BAU Disabled\n");
+	}
+
 	return 0;
 }
-early_param("nobau", setup_nobau);
+early_param("bau", setup_bau);
 
 /* base pnode in this partition */
 static int uv_base_pnode __read_mostly;
-- 
1.8.5.6

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[PATCH 0/2] Re-work UV BAU enable/disable logic, add documentation Alex Thorlton <athorlton@sgi.com> - 2016-03-21 18:20 +0100
  [PATCH 1/2] Disable UV BAU by default Alex Thorlton <athorlton@sgi.com> - 2016-03-21 18:20 +0100
    Re: [PATCH 1/2] Disable UV BAU by default Thomas Gleixner <tglx@linutronix.de> - 2016-03-23 12:30 +0100
      Re: [PATCH 1/2] Disable UV BAU by default Alex Thorlton <athorlton@sgi.com> - 2016-03-23 17:20 +0100
        Re: [PATCH 1/2] Disable UV BAU by default Alex Thorlton <athorlton@sgi.com> - 2016-03-23 18:30 +0100
        Re: [PATCH 1/2] Disable UV BAU by default Thomas Gleixner <tglx@linutronix.de> - 2016-03-23 18:30 +0100
  [PATCH 2/2] Add documentation for the bau parameter Alex Thorlton <athorlton@sgi.com> - 2016-03-21 18:20 +0100

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