Previously an MSHR with one or more invalidating targets would first
service all targets in the MSHR TargetList and then invalidate the
block. As a result any service snooping targets would lookup in the
cache and incorrectly find the block. This patch forces the
invalidation to happen when the first invalidating target is
encountered.
Change-Id: I9df15de24e1d351cd96f5a2c424d9a03d81c2cce
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
This patch changes an assertion that previously assumed that a non
invalidating snoop request should never be serviced by an
InvalidateReq MSHR. The MSHR serves as the ordering point for the
snooping packet. When the InvalidateResp reaches the cache the
snooping packet snoops the caches above to find the requested
block. One or more of the caches above will have the block since
earlier it has seen a WriteLineReq.
Change-Id: I0c147c8b5d5019e18bd34adf9af0fccfe431ae07
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
When the snoopFilter receives a response, it updates its state using
the hasSharers flag (indicates whether there are more than one copies
of the block in the caches above). The hasSharers flag of the packet
was previously populated when the request was traversing and snooping
the caches looking for the block.
1) When the response is coming from the memory-side port, its order
with respect to other responses is not necessarily preserved (e.g., a
request that arrived second to the xbar can get its response first). As
a result the snoopFilter might process responses out of order updating
its residency information using the non valid hasSharers flag which was
populated much earlier.
2) When the response is from an on-chip, the MSHRs preserve a well
defined order and the hasSharers flag should contain valid
information.
This patch changes the snoopFilter by avoiding the hasSharers flag
when the response is from the memory-side port.
Change-Id: Ib2d22a5b7bf3eccac64445127d2ea20ee74bb25b
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Previously, a WriteLineReq that missed in a cache would send out an
InvalidateReq if the block lookup failed or an UpgradeReq if the
block lookup succeeded but the block had sharers. This changes ensures
that a WriteLineReq always sends an InvalidateReq to invalidate all
copies of the block and satisfy the WriteLineReq.
Change-Id: I207ff5b267663abf02bc0b08aeadde69ad81be61
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Change-Id: Ie3beeef25331f84a0a5bcc17f7a791f4a829695b
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
This patch fixes an issue where an MSHR would incorrectly be perceived
to provide data to targets arriving after an InvalidateReq. To address
this the InvalidateReq is now treated as isForward, much like an
UpgradeReq that did not hit in the cache.
Change-Id: Ia878444d949539b5c33fd19f3e12b0b8a872275e
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Previously DPRINTFs printing information about a packet would use ad hoc
formats. This patch changes all DPRINTFs to use the print function
defined by the packet class, making the packet printing format more
uniform and easier to change.
Change-Id: Idd436a9758d4bf70c86a574d524648b2a2580970
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Previously all traffic generators would use the same value for write
requests. With this change traffic generators use their master id as
the payload of write requests making them more useful for the
memchecker.
Change-Id: Id1a6b8f02853789b108ef6003f4c32ab929bb123
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
A response to a ReadReq can either be a ReadResp or a
ReadRespWithInvalidate. As we add targets to an MSHR for a ReadReq we
assume that the response will be a ReadResp. When the response is
invalidating (ReadRespWithInvalidate) servicing more than one targets
can potentially violate the memory ordering. This change fixes the way
we handle a ReadRespWithInvalidate. When a cache receives a
ReadRespWithInvalidate we service only the first FromCPU target and
all the FromSnoop targets from the MSHR target list. The rest of the
FromCPU targets are deferred and serviced by a new request.
Change-Id: I75c30c268851987ee5f8644acb46f440b4eeeec2
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
Previously the information of whether a response was allocating or not
was a property of the MSHR. This change makes this flag a property of
the TargetList. Differernt TargetLists, e.g. the targets and the
deferred targets lists might have different values. Additionally, the
information about whether each of the target expects an allocating
response is stored inside the TargetList container. This allows for
repopulating the flag in case some of the targets are removed.
Change-Id: If3ec2516992f42a6d9da907009ffe3ab8d0d2021
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
This patch adds support for repopulating the flags of an MSHR
TargetList. The added functionality makes it possible to remove
targets from a TargetList without leaving it in an inconsistent state.
Change-Id: I3f7a8e97bfd3e2e49bebad056d11bbfb087aad91
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
Reviewed-by: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
HSA functions calls are still not supported properly with HSAIL, but
the recent AMP runtime modifications rely on being able to parse the
BRIG/HSAIL files that are extracted from the application binaries.
We need to parse the function call HSAIL definitions, but we do not
actually need to make the function calls.
The reason that this happens is that HCC appends a set of routines
to every HSAIL binary that it creates. These extra, unnecessary
routines exist in the HCC source as a file; this file is cat'd onto
everything that the compiler outputs before being assembled into the
application's binary. HCC does this because it might call these helper
functions. However, it doesn't actually appear to do so in the AMP
codes so we just parse these functions with the HSAIL parser and
then ignore them.
it's possible for the offset provided to an HSAIL mem inst to be a negative
value, however the variable we use to hold the offset is an unsigned type.
this can lead to excessively large offset values when the offset is negative,
which will almost certainly cause the access to go out of bounds.
In MessageBuffer the m_not_avail_count member is incremented but not used.
This causes an overflow reported by ASAN. This patch changes from an int to
Stats::Scalar, since the count is useful in debugging finite MessageBuffers.
This patch is the eighth patch in a series adding RISC-V to gem5, and
third of the bonus patches to the original series of five. It adds some
regression tests to RISC-V.
Regression tests included:
- se/00.hello
- se/02.insttest (split into several binaries which are not included due
to large size)
The tests added to 00.insttest will need to be build manually; to
facilitate this, a Makefile is included. The required toolchain and
compiler (riscv64-unknown-elf-gcc) can be built from the riscv-tools
GitHub repository at https://github.com/riscv/riscv-tools.
Note that because EBREAK only makes sense when gdb is running or while in
FS mode, it is not included in the linux-rv64i insttest. ERET is not
included because it does not make sense in SE mode and, in fact, causes
a panic by design.
Note also that not every system call is tested in linux-rv64i; of the ones
defined in linux/process.hh, some have been given numbers but not
definitions for the toolchain, or are merely stubs that always return 0. Of
the ones that do work properly, only a subset are tested due to similar
functionality.
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
RISC-V makes use of load-reserved and store-conditional instructions to
enable creation of lock-free concurrent data manipulation as well as
ACQUIRE and RELEASE semantics for memory ordering of LR, SC, and AMO
instructions (the latter of which do not follow LR/SC semantics). This
patch is a correction to patch 4, which added these instructions to the
implementation of RISC-V. It modifies locked_mem.hh and the
implementations of lr.w, sc.w, lr.d, and sc.d to apply the proper gem5
flags and return the proper values.
An important difference between gem5's LLSC semantics and RISC-V's LR/SC
ones, beyond the name, is that gem5 uses 0 to indicate failure and 1 to
indicate success, while RISC-V is the opposite. Strictly speaking, RISC-V
uses 0 to indicate success and nonzero to indicate failure where the
value would indicate the error, but currently only 1 is reserved as a
failure code by the ISA reference.
This is the seventh patch in the series which originally consisted of five
patches that added the RISC-V ISA to gem5. The original five patches added
all of the instructions and added support for more detailed CPU models and
the sixth patch corrected the implementations of Linux constants and
structs. There will be an eighth patch that adds some regression tests
for the instructions.
[Removed some commented-out code from locked_mem.hh.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
This is an add-on patch for the original series that implemented RISC-V
that improves the implementation of Linux emulation for SE mode. Basically
it cleans up linux/linux.hh by removing constants that haven't been
defined for the RISC-V Linux proxy kernel and rearranging the stat
struct so it aligns with RISC-V's implementation of it. It also adds
placeholders for system calls that have been given numbers in RISC-V
but haven't been given implementations yet. These system calls are
as follows:
- readlinkat
- sigprocmask
- ioctl
- clock_gettime
- getrusage
- getrlimit
- setrlimit
The first five patches implemented RISC-V with the base ISA and multiply,
floating point, and atomic extensions and added support for detailed
CPU models with memory timing.
[Fixed incompatibility with changes made from patch 1.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
Last of five patches adding RISC-V to GEM5. This patch adds support for
timing, minor, and detailed CPU models that was missing in the last four,
which basically consists of handling timing-mode memory accesses and
telling the minor and detailed models what a no-op instruction should
be (addi zero, zero, 0).
Patches 1-4 introduced RISC-V and implemented the base instruction set,
RV64I, and added the multiply, floating point, and atomic memory
extensions, RV64MAFD.
[Fixed compatibility with edit from patch 1.]
[Fixed compatibility with hg copy edit from patch 1.]
[Fixed some style errors in locked_mem.hh.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
Fourth of five patches adding RISC-V to GEM5. This patch adds the RV64A
extension, which includes atomic memory instructions. These instructions
atomically read a value from memory, modify it with a value contained in a
source register, and store the original memory value in the destination
register and modified value back into memory. Because this requires two
memory accesses and GEM5 does not support two timing memory accesses in
a single instruction, each of these instructions is split into two micro-
ops: A "load" micro-op, which reads the memory, and a "store" micro-op,
which modifies and writes it back. Each atomic memory instruction also has
two bits that acquire and release a lock on its memory location.
Additionally, there are atomic load and store instructions that only either
load or store, but not both, and can acquire or release memory locks.
Note that because the current implementation of RISC-V only supports one
core and one thread, it doesn't make sense to make use of AMO instructions.
However, they do form a standard extension of the RISC-V ISA, so they are
included mostly as a placeholder for when multithreaded execution is
implemented. As a result, any tests for their correctness in a future
patch may be abbreviated.
Patch 1 introduced RISC-V and implemented the base instruction set, RV64I;
patch 2 implemented the integer multiply extension, RV64M; and patch 3
implemented the single- and double-precision floating point extensions,
RV64FD.
Patch 5 will add support for timing, minor, and detailed CPU models that
isn't present in patches 1-4.
[Added missing file amo.isa]
[Replaced information removed from initial patch that was missed during
division into multiple patches.]
[Fixed some minor formatting issues.]
[Fixed oversight where LR and SC didn't have both AQ and RL flags.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
Third of five patches adding RISC-V to GEM5. This patch adds the RV64FD
extensions, which include single- and double-precision floating point
instructions.
Patch 1 introduced RISC-V and implemented the base instruction set, RV64I
and patch 2 implemented the integer multiply extension, RV64M.
Patch 4 will implement the atomic memory instructions, RV64A, and patch
5 will add support for timing, minor, and detailed CPU models that is
missing from the first four patches.
[Fixed exception handling in floating-point instructions to conform better
to IEEE-754 2008 standard and behavior of the Chisel-generated RISC-V
simulator.]
[Fixed style errors in decoder.isa.]
[Fixed some fuzz caused by modifying a previous patch.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
Second of five patches adding RISC-V to GEM5. This patch adds the
RV64M extension, which includes integer multiply and divide instructions.
Patch 1 introduced RISC-V and implemented the base instruction set, RV64I.
Patch 3 will implement the floating point extensions, RV64FD; patch 4 will
implement the atomic memory instructions, RV64A; and patch 5 will add
support for timing, minor, and detailed CPU models that is missing from
the first four patches.
[Added mulw instruction that was missed when dividing changes among
patches.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
First of five patches adding RISC-V to GEM5. This patch introduces the
base 64-bit ISA (RV64I) in src/arch/riscv for use with syscall emulation.
The multiply, floating point, and atomic memory instructions will be added
in additional patches, as well as support for more detailed CPU models.
The loader is also modified to be able to parse RISC-V ELF files, and a
"Hello world\!" example for RISC-V is added to test-progs.
Patch 2 will implement the multiply extension, RV64M; patch 3 will implement
the floating point (single- and double-precision) extensions, RV64FD;
patch 4 will implement the atomic memory instructions, RV64A, and patch 5
will add support for timing, minor, and detailed CPU models that is missing
from the first four patches (such as handling locked memory).
[Removed several unused parameters and imports from RiscvInterrupts.py,
RiscvISA.py, and RiscvSystem.py.]
[Fixed copyright information in RISC-V files copied from elsewhere that had
ARM licenses attached.]
[Reorganized instruction definitions in decoder.isa so that they are sorted
by opcode in preparation for the addition of ISA extensions M, A, F, D.]
[Fixed formatting of several files, removed some variables and
instructions that were missed when moving them to other patches, fixed
RISC-V Foundation copyright attribution, and fixed history of files
copied from other architectures using hg copy.]
[Fixed indentation of switch cases in isa.cc.]
[Reorganized syscall descriptions in linux/process.cc to remove large
number of repeated unimplemented system calls and added implmementations
to functions that have received them since it process.cc was first
created.]
[Fixed spacing for some copyright attributions.]
[Replaced the rest of the file copies using hg copy.]
[Fixed style check errors and corrected unaligned memory accesses.]
[Fix some minor formatting mistakes.]
Signed-off by: Alec Roelke
Signed-off by: Jason Lowe-Power <jason@lowepower.com>
If the cache access mode is parallel, i.e. "sequential_access" parameter
is set to "False", tags and data are accessed in parallel. Therefore,
the hit_latency is the maximum latency between tag_latency and
data_latency. On the other hand, if the cache access mode is
sequential, i.e. "sequential_access" parameter is set to "True",
tags and data are accessed sequentially. Therefore, the hit_latency
is the sum of tag_latency plus data_latency.
Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
This function was used by the now-defunct InOrderCPU model. Since this
model is no longer in gem5, this function was not called from anywhere in
the code.
Changeset 11701 only serialized the useful portion of of an ethernet packets'
payload. However, the device models expect each ethernet packet to contain
a 16KB buffer, even if there is no data in it. This patch adds a 'bufLength'
field to EthPacketData so the original size of the packet buffer can always
be unserialized.
Reported-by: Gabor Dozsa <Gabor.Dozsa@arm.com>
There has been some problem when using address and undefined-behavior
sanitizers at the same time. This patch will look for the special case
where both are enabled at once and change the flags passed to the compiler
to reflect this.
Add an option, --checker/-c, to style.py that selects individual style
checkers to apply. When this option isn't specified, the script
defaults to all available style checkers. The option may be specified
multiple times to run multiple style checkers.
The option, --fix/-f, can be specified to automatically fix style
violations.
Change-Id: Id7597fba6b65cecfa17a88b1c87c8a4c8315af59
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
This patch updates the git-pre-commit hook to check the files as they
will be after the commit, instead of as they are currently, this way we
prevent the undesired situation:
- unstylish modification of a file
- stage said file for commit
- try to commit and fail due to style
- fix style, forgetting staging changes
- try to commit and fail, as although the changes staged are not
styly, the current content of the file is.
Change-Id: I5cc3f783375d9e4162e310e176103ebbf0a59023
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
[andreas.sandberg@arm.com: Rebased ontop of latest gem5]
the GPUExecContext context currently stores a reference to its parent WF's
GPUISA object, however there are some special instructions that do not have
an associated WF. when these objects are constructed they set their WF pointer
to null, which causes the GPUExecContext to segfault when trying to
dereference
the WF pointer to get at the WF's GPUISA object. here we change the GPUISA
reference in the GPUExecContext class to a pointer so that it may be set to
null.
UBSAN flags this operation because it detects that arg is being cast directly
to an unsigned type, argBits. this patch fixes this by first casting the
value to a signed int type, then reintrepreting the raw bits of the signed
int into argBits.
SequencerMsg is autogenerated by slicc scripts and the MessageSizeType is
initialized to the max enume value by default. The DMASequencer pushes this
message to the mandatory queue and since the MessageSizeType is unitialized,
string_to_MessageSizeType() function used by traces to print the message fails
with a panic. This patch avoids this problem by initializing MessageSizeType
of SequencerMsg to Request_Control.
This patch avoids compiling ALPHA six times as part of running
'util/regress', and instead relis on NULL with different protocols to
run the rubytest. All we need is the memory system, so there is really
no need to compile the ISA over and over again.
The one downside is the removal of running 'hello' for the variuos
ALPHA and protocol combinations, but if this is a concern we should
rather beef up the synthetic tests for the variuos protocols.
--HG--
rename : build_opts/NULL => build_opts/NULL_MESI_Two_Level
rename : build_opts/NULL => build_opts/NULL_MOESI_CMP_directory
rename : build_opts/NULL => build_opts/NULL_MOESI_CMP_token
rename : build_opts/NULL => build_opts/NULL_MOESI_hammer
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MESI_Two_Level/config.ini => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MESI_Two_Level/config.ini
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MESI_Two_Level/simerr => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MESI_Two_Level/simerr
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MESI_Two_Level/simout => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MESI_Two_Level/simout
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MESI_Two_Level/stats.txt => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MESI_Two_Level/stats.txt
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_directory/config.ini => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_directory/config.ini
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_directory/simerr => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_directory/simerr
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_directory/simout => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_directory/simout
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_directory/stats.txt => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_directory/stats.txt
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_token/config.ini => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_token/config.ini
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_token/simerr => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_token/simerr
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_token/simout => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_token/simout
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_CMP_token/stats.txt => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_CMP_token/stats.txt
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_hammer/config.ini => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_hammer/config.ini
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_hammer/simerr => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_hammer/simerr
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_hammer/simout => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_hammer/simout
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby-MOESI_hammer/stats.txt => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby-MOESI_hammer/stats.txt
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby/config.ini => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby/config.ini
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby/simerr => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby/simerr
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby/simout => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby/simout
rename : tests/quick/se/60.rubytest/ref/alpha/linux/rubytest-ruby/stats.txt => tests/quick/se/60.rubytest/ref/null/none/rubytest-ruby/stats.txt
fixes to appease clang++. tested on:
Ubuntu clang version 3.5.0-4ubuntu2~trusty2
(tags/RELEASE_350/final) (based on LLVM 3.5.0)
Ubuntu clang version 3.6.0-2ubuntu1~trusty1
(tags/RELEASE_360/final) (based on LLVM 3.6.0)
the fixes address the following five issues:
1) the exec continuations in gpu_static_inst.hh were marked
as protected when they should be public. here we mark
them as public
2) the Abs instruction uses std::abs() in its execute method.
because Abs is templated, it can also operate on U32 and U64,
types, which cause Abs::execute() to pass uint32_t and uint64_t
types to std::abs() respectively. this triggers a warning
because std::abs() has no effect in this case. to rememdy this
we add template specialization for the execute() method of Abs
when its template paramter is U32 or U64.
3) Some potocols that utilize the code in cprintf.hh were missing
includes to BoolVec.hh, which defines operator<< for the BoolVec
type. This would cause issues when the generated code would try
to pass a BoolVec type to a method in cprintf.hh that used
operator<< on an instance of a BoolVec.
4) Surprise, clang doesn't like it when you clobber all the bits
in a newly allocated object. I.e., this code:
tlb = new GpuTlbEntry\[size\];
std::memset(tlb, 0, sizeof(GpuTlbEntry) \* size);
Let's use std::vector to track the TLB entries in the GpuTlb now...
5) There were a few variables used only in DPRINTFs, so we mark them
with M5_VAR_USED.
This patch adds the ability for an application to request dist-gem5 to begin/
end synchronization using an m5 op. When toggling on sync, all nodes agree
on the next sync point based on the maximum of all nodes' ticks. CPUs are
suspended until the sync point to avoid sending network messages until sync has
been enabled. Toggling off sync acts like a global execution barrier, where
all CPUs are disabled until every node reaches the toggle off point. This
avoids tricky situations such as one node hitting a toggle off followed by a
toggle on before the other nodes hit the first toggle off.
DMA sequencers and protocols can currently only issue one DMA access at
a time. This patch implements the necessary functionality to support
multiple outstanding DMA requests in Ruby.
Currently, all the network devices create a 16K buffer for the 'data' field
in EthPacketData, and use 'length' to keep track of the size of the packet
in the buffer. This patch introduces the 'simLength' parameter to
EthPacketData, which is used to hold the effective length of the packet used
for all timing calulations in the simulator. Serialization is performed using
only the useful data in the packet ('length') and not necessarily the entire
original buffer.
