In order for a system object to work in SE mode and FS mode, it has to either
always require a platform object even in SE mode, or get rid of the
requirement all together. Making SE mode carry around unnecessary/unused bits
of FS seems less than ideal, so I decided to go with the second option. The
platform pointer in the System class was used for exactly one purpose, a path
for the Alpha Linux system object to get to the real time clock and read its
frequency so that it could short cut the loops_per_jiffy calculation. There
was also a copy and pasted implementation in MIPS, but since it was only there
because it was there in Alpha I still count that as one use.
This change reverses the mechanism that communicates the RTC frequency so that
the Tsunami platform object pushes it up to the AlphaSystem object. This is
slightly less specific than it could be because really only the
AlphaLinuxSystem uses it. Because the intrFrequency function on the Platform
class was no longer necessary (and unimplemented on anything but Alpha) it was
eliminated.
After this change, a platform will need to have a system, but a system won't
have to have a platform.
All of the classes will now be available in both modes, and only
GenericPageTableFault will continue to check the mode for conditional
compilation. It uses a process object to handle the fault in SE mode, and
for now those aren't available in FS mode.
This constant will have the same value as FULL_SYSTEM but will not be usable
by the preprocessor. It can be substituted into places where FULL_SYSTEM is
used in a C++ context and will make it easier to find which parts of the
simulator still use FULL_SYSTEM with the preprocessor using grep.
Initialize flags via the Event constructor instead of calling
setFlags() in the body of the derived class's constructor. I
forget exactly why, but this made life easier when implementing
multi-queue support.
Also rename Event::getFlags() to isFlagSet() to better match
common usage, and get rid of some unused Event methods.
Use exitSimLoop() function instead of explicitly scheduling
on mainEventQueue (which won't work once we go to multiple
event queues). Also introduced a local params variable to
shorten a lot of expressions.
It was technically possible but clumsy to determine what endianness a guest
was configured with using the state in byteswap.hh. This change makes that
information available more directly.
Also get rid of unused (and mildly redundant) ByteOrderDiffers constant.
Only create a memory ordering violation when the value could have changed
between two subsequent loads, instead of just when loads go out-of-order
to the same address. While not very common in the case of Alpha, with
an architecture with a hardware table walker this can happen reasonably
frequently beacuse a translation will miss and start a table walk and
before the CPU re-schedules the faulting instruction another one will
pass it to the same address (or cache block depending on the dendency
checking).
This patch has been tested with a couple of self-checking hand crafted
programs to stress ordering between two cores.
The performance improvement on SPEC benchmarks can be substantial (2-10%).
Do some minor cleanup of some recently added comments, a warning, and change
other instances of stack extension to be like what's now being done for x86.
Nothing big here, but when you have an address that is not in the page table request to be allocated, if it falls outside of the maximum stack range all you get is a page fault and you don't know why. Add a little warn() to explain it a bit. Also add some comments and alter logic a little so that you don't totally ignore the return value of checkAndAllocNextPage().
We were getting a spurious warning in the regressions that turned
out to be due to having the wrong value for TGT_MAP_ANONYMOUS for
Power Linux, but in the process of tracking it down I ended up
doing some cleanup of the mmap handling in general.
This is similar to guards on mercurial queues and they're used for selecting
which files are compiled into some given object. We already do something
similar, but it's mostly hard coded for the m5 binary and the m5 library
and I'd like to make it more flexible to better support the unittests
At the same time, rename the trace flags to debug flags since they
have broader usage than simply tracing. This means that
--trace-flags is now --debug-flags and --trace-help is now --debug-help
This patch prevents not executed conditional instructions marked as
IsQuiesce from stalling the pipeline indefinitely. If the instruction
is not executed the quiesceSkip psuedoinst is called which schedules a
wakes up call to the fetch stage.
Some ISAs (like ARM) relies on hardware page table walkers. For those ISAs,
when a TLB miss occurs, initiateTranslation() can return with NoFault but with
the translation unfinished.
Instructions experiencing a delayed translation due to a hardware page table
walk are deferred until the translation completes and kept into the IQ. In
order to keep track of them, the IQ has been augmented with a queue of the
outstanding delayed memory instructions. When their translation completes,
instructions are re-executed (only their initiateAccess() was already
executed; their DTB translation is now skipped). The IEW stage has been
modified to support such a 2-pass execution.
Setup initial timesync event in initState or loadState so that curTick has
been updated to the new value, otherwise the event is scheduled in the past.
Moving the definition of NoFault into fault.hh doesn't bring any new
dependencies with it, and allows some files to include just fault.hh which has
less baggage. NoFault will still be available to everything that includes
faults.hh because it includes fault.hh.
M5 skips over any simulated time where it doesn't have any work to do. When
the simulation is active, the time skipped is short and the work done at any
point in time is relatively substantial. If the time between events is long
and/or the work to do at each event is small, it's possible for simulated time
to pass faster than real time. When running a benchmark that can be good
because it means the simulation will finish sooner in real time. When
interacting with the real world through, for instance, a serial terminal or
bridge to a real network, this can be a problem. Human or network response time
could be greatly exagerated from the perspective of the simulation and make
simulated events happen "too soon" from an external perspective.
This change adds the capability to force the simulation to run no faster than
real time. It does so by scheduling a periodic event that checks to see if
its simulated period is shorter than its real period. If it is, it stalls the
simulation until they're equal. This is called time syncing.
A future change could add pseudo instructions which turn time syncing on and
off from within the simulation. That would allow time syncing to be used for
the interactive parts of a session but then turned off when running a
benchmark using the m5 utility program inside a script. Time syncing would
probably not happen anyway while running a benchmark because there would be
plenty of work for M5 to do, but the event overhead could be avoided.
There's no reason for it to derive from SimLoopExitEvent.
This whole drain thing needs to be redone eventually,
but this is a stopgap to make later changes to
SimLoopExitEvent feasible.
