linux-kernel - [PATCH 4/4] xen/acpi: Workaround broken BIOSes exporting non-existing C-states.

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Date:	Thu, 26 Apr 2012 14:29:25 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH 4/4] xen/acpi: Workaround broken BIOSes exporting non-existing C-states.

We did a similar check for the P-states but did not do it for
the C-states. What we want to do is ignore cases where the DSDT
has definition for sixteen CPUs, but the machine only has eight
CPUs and we get:
xen-acpi-processor: (CX): Hypervisor error (-22) for ACPI CPU14

Reported-by: Tobias Geiger <tobias.geiger@...o.info>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
 drivers/xen/xen-acpi-processor.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/xen/xen-acpi-processor.c b/drivers/xen/xen-acpi-processor.c
index 174b565..0b48579 100644
--- a/drivers/xen/xen-acpi-processor.c
+++ b/drivers/xen/xen-acpi-processor.c
@@ -128,7 +128,10 @@ static int push_cxx_to_hypervisor(struct acpi_processor *_pr)
 			pr_debug("     C%d: %s %d uS\n",
 				 cx->type, cx->desc, (u32)cx->latency);
 		}
-	} else
+	} else if (ret != -EINVAL)
+		/* EINVAL means the ACPI ID is incorrect - meaning the ACPI
+		 * table is referencing a non-existing CPU - which can happen
+		 * with broken ACPI tables. */
 		pr_err(DRV_NAME "(CX): Hypervisor error (%d) for ACPI CPU%u\n",
 		       ret, _pr->acpi_id);

-- 
1.7.7.5

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