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dev,arm: remove and recreate timer events around drains

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Having timer events stored in checkpoints complicates Kvm
execution.  We change the timer behavior so that it always
deschedules any pending events on a drain() and recreates
them on a drainResume(), thus they will never appear in
checkpoints henceforth.  This pattern of behavior makes
it simpler to handle Kvm execution, where the hardware
performs the timer function directly.

Change-Id: Ia218868c69350d96e923c640634d492b5c19cd3f
Reviewed-on: https://gem5-review.googlesource.com/3541
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
Curtis Dunham
2017-05-18 21:18:48 +00:00
committed by Andreas Sandberg
parent b829b4a8e4
commit e2a049e089
2 changed files with 25 additions and 16 deletions
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32
src/dev/arm/generic_timer.cc
View File

@@ -179,13 +179,6 @@ ArchTimer::serialize(CheckpointOut &cp) const
paramOut(cp, "control_serial", _control);
SERIALIZE_SCALAR(_counterLimit);
SERIALIZE_SCALAR(_offset);
const bool event_scheduled(_counterLimitReachedEvent.scheduled());
SERIALIZE_SCALAR(event_scheduled);
if (event_scheduled) {
const Tick event_time(_counterLimitReachedEvent.when());
SERIALIZE_SCALAR(event_time);
}
}
void
@@ -197,13 +190,24 @@ ArchTimer::unserialize(CheckpointIn &cp)
// compatibility.
if (!UNSERIALIZE_OPT_SCALAR(_offset))
_offset = 0;
bool event_scheduled;
UNSERIALIZE_SCALAR(event_scheduled);
if (event_scheduled) {
Tick event_time;
UNSERIALIZE_SCALAR(event_time);
_parent.schedule(_counterLimitReachedEvent, event_time);
}
// We no longer schedule an event here because we may enter KVM
// emulation. The event creation is delayed until drainResume().
}
DrainState
ArchTimer::drain()
{
if (_counterLimitReachedEvent.scheduled())
_parent.deschedule(_counterLimitReachedEvent);
return DrainState::Drained;
}
void
ArchTimer::drainResume()
{
updateCounter();
}
void

9
src/dev/arm/generic_timer.hh
View File

@@ -1,5 +1,5 @@
/*
* Copyright (c) 2013, 2015 ARM Limited
* Copyright (c) 2013, 2015, 2017 ARM Limited
* All rights reserved.
*
* The license below extends only to copyright in the software and shall
@@ -102,7 +102,7 @@ class SystemCounter : public Serializable
};
/// Per-CPU architected timer.
class ArchTimer : public Serializable
class ArchTimer : public Serializable, public Drainable
{
public:
class Interrupt
@@ -188,9 +188,14 @@ class ArchTimer : public Serializable
/// Returns the value of the counter which this timer relies on.
uint64_t value() const;
// Serializable
void serialize(CheckpointOut &cp) const override;
void unserialize(CheckpointIn &cp) override;
// Drainable
DrainState drain() override;
void drainResume() override;
private:
// Disable copying
ArchTimer(const ArchTimer &t);