Attachment 575398 Details for Bug 808033 – [RHEL6.3 seabios PATCH] Replace level gpe event with edge gpe event for hot-plug handlers

[patch] [RHEL6.3 seabios PATCH] Replace level gpe event with edge gpe event for hot-plug handlers

0001-Replace-level-gpe-event-with-edge-gpe-event-for-hot-.patch (text/plain), 2.24 KB, created by Igor Mammedov on 2012-04-05 12:49:19 UTC

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Creator: Igor Mammedov

Created: 2012-04-05 12:49:19 UTC

Size: 2.24 KB

patch

obsolete

>From c861832260904c5310b96ebfe9d6873ae40c8c3e Mon Sep 17 00:00:00 2001
>From: Igor Mammedov <imammedo@redhat.com>
>Date: Thu, 5 Apr 2012 16:22:18 +0200
>Subject: [RHEL6.3 seabios PATCH] Replace level gpe event with edge gpe event for hot-plug handlers
>
>BZ#808033
>Upstream: 9c6635bd48d39a1d17d0a73df6e577ef6bd0037c
>
>in current code, pci hot-plug gpe event handler is defined as
>a level one "_L01"
>
>1. hw adds device, sets GPE.1 bit and sends SCI
>2. OSPM gets SCI, reads GPE00.sts and masks GPE.1 bit in GPE00.en
>3. OSPM executes _L01
>4. hw adds second device and sets GPE.1 bit but SCI is not asserted
>since GPE00.en masks event
>5. OSPM resets GPE.1 bit in GPE00.sts and umasks it in GPE00.en
>
>as result event for step 4 is lost because step 5 clears it and OS
>will not see added second device.
>
>ACPI 50 spec: 5.6.4 General-Purpose Event Handling
>defines GPE event handling as following:
>
>1. Disables the interrupt source (GPEx_BLK EN bit).
>2. If an edge event, clears the status bit.
>3. Performs one of the following:
>* Dispatches to an ACPI-aware device driver.
>* Queues the matching control method for execution.
>* Manages a wake event using device _PRW objects.
>4. If a level event, clears the status bit.
>5. Enables the interrupt source.
>
>Switching from level to edge event handler reduces chances to
>hit race window.
>
>Same applies to cpu-hotplug, so switch it to edge handler as well.
>
>Tested with RHEL6, 3.3.+ kernel, winxp, and w2008r2, and I wasn't
>able to trigger race after using edge event handler.
>
>Credits to Michael S. Tsirkin for idea.
>
>Signed-off-by: Igor Mammedov <imammedo@redhat.com>
>---
> src/acpi-dsdt.dsl |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/src/acpi-dsdt.dsl b/src/acpi-dsdt.dsl
>index 62fa26a..61dc7d4 100644
>--- a/src/acpi-dsdt.dsl
>+++ b/src/acpi-dsdt.dsl
>@@ -817,7 +817,7 @@ DefinitionBlock (
>                 Notify(\_SB.PCI0.S##nr, 3)                        \
>             }
> 
>-        Method(_L01) {
>+        Method(_E01) {
>             gen_pci_hotplug(1)
>             gen_pci_hotplug(2)
>             gen_pci_hotplug(3)
>@@ -853,7 +853,7 @@ DefinitionBlock (
>             Return (0x01)
> 
>         }
>-        Method(_L02) {
>+        Method(_E02) {
>             // CPU hotplug event
>             Return(\_SB.PRSC())
>         }
>-- 
>1.7.1
>

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Attachments on bug 808033: 574501 | 575088 | 575398