The updates to the x87 caused the stats for several regressions to
change. This was mainly caused by the addition of a working 32-bit and
80-bit FP load instruction and xsave support.
The kvm-based CPU module requires support for POSIX timers. This
changeset adds a check for POSIX timers and ensures that gem5 is
linked with librt if necessary. KVM support is disabled if POSIX
timers are not supported by the host. This fixes a compilation issue
for some glibc versions where clock_nanosleep and timer_create are in
different libraries.
This changeset updates the external library to git revision
52b6190b4e. This update includes changes that fix compilation errors
on old gcc versions and fixes to test a case that affect ICC.
In order to support m5ops in virtualized environments, we need to use
a memory mapped interface. This changeset adds support for that by
reserving 0xFFFF0000-0xFFFFFFFF and mapping those to the generic IPR
interface for m5ops. The mapping is done in the
X86ISA::TLB::finalizePhysical() which means that it just works for all
of the CPU models, including virtualized ones.
In order to support m5ops on virtualized CPUs, we need to either
intercept hypercall instructions or provide a memory mapped m5ops
interface. Since KVM does not normally pass the results of hypercalls
to userspace, which makes that method unfeasible. This changeset
introduces support for m5ops using memory mapped mmapped IPRs. This is
implemented by adding a class of "generic" IPRs which are handled by
architecture-independent code. Such IPRs always have bit 63 set and
are handled by handleGenericIprRead() and
handleGenericIprWrite(). Platform specific impementations of
handleIprRead and handleIprWrite should use
GenericISA::isGenericIprAccess to determine if an IPR address should
be handled by the generic code instead of the architecture-specific
code. Platforms that don't need their own IPR support can reuse
GenericISA::handleIprRead() and GenericISA::handleIprWrite().
The x87 FPU supports three floating point formats: 32-bit, 64-bit, and
80-bit floats. The current gem5 implementation supports 32-bit and
64-bit floats, but only works correctly for 64-bit floats. This
changeset fixes the 32-bit float handling by correctly loading and
rounding (using truncation) 32-bit floats instead of simply truncating
the bit pattern.
80-bit floats are loaded by first loading the 80-bits of the float to
two temporary integer registers. A micro-op (cvtint_fp80) then
converts the contents of the two integer registers to the internal FP
representation (double). Similarly, when storing an 80-bit float,
there are two conversion routines (ctvfp80h_int and cvtfp80l_int) that
convert an internal FP register to 80-bit and stores the upper 64-bits
or lower 32-bits to an integer register, which is the written to
memory using normal integer stores.
X87 store instructions typically loads and pops the top value of the
stack and stores it in memory. The current implementation pops the
stack at the same time as the floating point value is loaded to a
temporary register. This will corrupt the state of the x87 stack if
the store fails. This changeset introduces a pop87 micro-instruction
that pops the stack and uses this instruction in the affected
macro-instructions to pop the stack after storing the value to memory.
Instruction events are currently ignored when executing in KVM. This
changeset adds support for triggering KVM exits based on instruction
counts using hardware performance counters. Depending on the
underlying performance counter implementation, there might be some
inaccuracies due to instructions being counted in the host kernel when
entering/exiting KVM.
Due to limitations/bugs in Linux's performance counter interface, we
can't reliably change the period of an overflow counter. We work
around this issue by detaching and reattaching the counter if we need
to reconfigure it.
This changeset adds support for synchronizing the FPU and SIMD state
of a virtual x86 CPU with gem5. It supports both the XSave API and the
KVM_(GET|SET)_FPU kernel API. The XSave interface can be disabled
using the useXSave parameter (in case of kernel
issues). Unfortunately, KVM_(GET|SET)_FPU interface seems to be buggy
in some kernels (specifically, the MXCSR register isn't always
synchronized), which means that it might not be possible to
synchronize MXCSR on old kernels without the XSave interface.
This changeset depends on the __float80 type in gcc and might not
build using llvm.
The x87 FPU on x86 supports extended floating point. We currently
handle all floating point on x86 as double and don't support 80-bit
loads/stores. This changeset add a utility function to load and
convert 80-bit floats to doubles (loadFloat80) and another function to
store doubles as 80-bit floats (storeFloat80). Both functions use
libfputils to do the conversion in software. The functions are
currently not used, but are required to handle floating point in KVM
and to properly support all x87 loads/stores.
This changeset includes libfputils from revision bbf0d61d75. This
library can be used to convert to and from 80-bit floats and query the
type of an 80-bit float, which is needed to support the x87 FPU.
There are cases when the segment registers in gem5 are not compatible
with VMX. This changeset works around all known such issues. Specifically:
* The accessed bits in CS, SS, DD, ES, FS, GS are forced to 1.
* The busy bit in TR is forced to 1.
* The protection level of SS is forced to the same protection level as
CS. The difference /seems/ to be caused by a bug in gem5's x86
implementation.
Apparently only stats.txt was updated the last time, so
this changeset updates other reference output files
(config.ini, simout, simerr, ruby.stats) so that
test output diffs should not be cluttered with irrelevant
changes. There are a few stats.txt updates too, but
they are in the minority.
This changeset adds support for KVM on x86. Full support is split
across a number of commits since some features are relatively
complex. This changeset includes support for:
* Integer state synchronization (including segment regs)
* CPUID (gem5's CPUID values are inserted into KVM)
* x86 legacy IO (remapped and handled by gem5's memory system)
* Memory mapped IO
* PCI
* MSRs
* State dumping
Most of the functionality is fairly straight forward. There are some
quirks to support PCI enumerations since this is done in the TLB(!) in
the simulated CPUs. We currently replicate some of that code.
Unlike the ARM implementation, the x86 implementation of the virtual
CPU does not use the cycles hardware counter. KVM on x86 simulates the
time stamp counter (TSC) in the kernel. If we just measure host cycles
using perfevent, we might end up measuring a slightly different number
of cycles. If we don't get the cycle accounting right, we might end up
rewinding the TSC, with all kinds of chaos as a result.
An additional feature of the KVM CPU on x86 is extended state
dumping. This enables Python scripts controlling the simulator to
request dumping of a subset of the processor state. The following
methods are currenlty supported:
* dumpFpuRegs
* dumpIntRegs
* dumpSpecRegs
* dumpDebugRegs
* dumpXCRs
* dumpXSave
* dumpVCpuEvents
* dumpMSRs
Known limitations:
* M5 ops are currently not supported.
* FPU synchronization is not supported (only affects CPU switching).
Both of the limitations will be addressed in separate commits.
The KVM base class incorrectly assumed that handleIprRead and
handleIprWrite both return ticks. This is not the case, instead they
return cycles. This changeset converts the returned cycles to ticks
when handling IPR accesses.
There is a possibility that the timespec used to arm a timer becomes
zero if the number of ticks used when arming a timer is close to the
resolution of the timer. Due to the semantics of POSIX timers, this
actually disarms the timer. This changeset fixes this issue by
eliminating the rounding error (we always round away from zero
now). It also reuses the minimum number of cycles, which were
previously only used for cycle-based timers, to calculate a more
useful resolution.
This changeset adds the convX87XTagsToTags() and convX87TagsToXTags()
which convert between the tag formats in the FTW register and the
format used in the xsave area. The conversion from to the x87 FTW
representation is currently loses some information since it does not
reconstruct the valid/zero/special flags which are not included in the
xsave representation.
The order between updating and using arg_num in
PseudoInst::pseudoInst() is currently undefined. This changeset
explicitly updates arg_num after it has been used to extract an
argument.
--HG--
extra : rebase_source : 67c46dc3333d16ce56687ee8aea41ce6c6d133bb
This patch ensures that a dequeue event is not scheduled if the memory
controller is waiting for a retry already. Without this check it is
possible for the controller to attempt sending something whilst
already having one packet that is in retry, thus causing the bus to
have an assertion failure.
This patch fixes an issue which prevented gem5 from running when built
using swig 2.0.9 and 2.0.10. The generated event.py tried to import
m5.internal which in turn relied on importing event. This patch seems
to fix the problem, and so far has not caused any other issues.
In order to support hardware virtualization, we need to be able to
check if there are any interrupts pending irregardless of the
rflags.intf value. This changeset adds the checkInterruptsRaw() method
to the x86 interrupt control. It returns true if there are pending
interrupts that can be delivered as soon as the CPU is ready for
interrupt delivery.
Recent changes added setting of system-wide cache line size and these settings
occur in the top-level configs (se.py and fs.py). This setting also needs to
take place in ruby_fs.py. This change sets the cache line size as appropriate.
The Topology source sets up input and output buffers for each of the external
nodes of a topology by indexing on Ruby's generated controller unique IDs.
These unique IDs are found by adding the MachineType_base_number to the version
number of each controller (see any generated *_Controller.cc - init() calls
getToNetQueue and getFromNetQueue using m_version + base). However, the
Topology object used the cntrl_id - which is required to be unique across all
controllers - to index the controllers list as they are being connected to
their input and output buffers. If the cntrl_ids did not match the Ruby unique
ID, the throttles end up connected to incorrectly indexed nodes in the network,
resulting in packets traversing incorrect network paths. This patch fixes the
Topology indexing scheme by using the Ruby unique ID to match that of the
SimpleNetwork buffer vectors.
Previously, the LSQ would instantiate MaxThreads LSQUnits in the body of it's
object, but it would only initialize numThreads LSQUnits as specified by the
user. This had the effect of leaving some LSQUnits uninitialized when the
number of threads was less than MaxThreads, and when adding statistics to the
LSQUnit that must be initialized, this caused the stats initialization check to
fail. By dynamically instantiating LSQUnits, they are all initialized and this
avoids uninitialized LSQUnits from floating around during runtime.
The previous changeset (9816) that fixes the use of max ticks introduced the
variable cpt_starttick, which is used for setting the relative max tick.
Unfortunately, with checkpointing at an instruction count or with simpoints,
the checkpoint tick is not stored conveniently, so to ensure that cpt_starttick
is initialized, set it to 0. Also, if using --rel-max-tick, check the use of
instruction counts or simpoints to warn the user that the max tick setting does
not include the checkpoint ticks.
The previous changeset (9863:9483739f83ee) used STL vector containers to
dynamically allocate stats in the Ruby SimpleNetwork, Switch and Throttle. For
gcc versions before at least 4.6.3, this causes the standard vector allocator
to call Stats copy constructors (a no-no, since stats should be allocated in
the body of each SimObject instance). Since the size of these stats arrays is
known at compile time (NOTE: after code generation), this patch changes their
allocation to be static rather than using an STL vector.
The routers are created before the network class. This results in the routers
becoming children of the first link they are connected to and they get generic
names like int_node and node_b. This patch creates the network object first
and passes it to the topology creation function. Now the routers are children
of the network object and names are much more sensible.
This patch adds the config ini string as a tooltip that can be
displayed in most browsers rendering the resulting svg. Certain
characters are modified for HTML output.
Tested on chrome and firefox.
This patch is adding a splash of colour to the dot output to make it
easier to distinguish objects of different types. As a bonus, the
pastel-colour palette also makes the output look like a something from
the 21st century.
This patch adds the class name to the label, creates some more space
by increasing the rank separation, and additionally outputs the graph
as an editable SVG in addition to the PDF.
