changeset a06e95c99294 in /z/repo/m5
details: http://repo.m5sim.org/m5?cmd=changeset;node=a06e95c99294
description:
CPU: Added comments to address translation classes.
diffstat:
1 file changed, 62 insertions(+), 2 deletions(-)
src/cpu/translation.hh | 64 ++++++++++++++++++++++++++++++++++++++++++++++--
diffs (153 lines):
diff -r 2ab58c54de63 -r a06e95c99294 src/cpu/translation.hh
--- a/src/cpu/translation.hh Tue Mar 23 22:49:43 2010 -0700
+++ b/src/cpu/translation.hh Thu Mar 25 12:43:52 2010 +0000
@@ -35,6 +35,16 @@
#include "sim/tlb.hh"
+/**
+ * This class captures the state of an address translation. A translation
+ * can be split in two if the ISA supports it and the memory access crosses
+ * a page boundary. In this case, this class is shared by two data
+ * translations (below). Otherwise it is used by a single data translation
+ * class. When each part of the translation is finished, the finish
+ * function is called which will indicate whether the whole translation is
+ * completed or not. There are also functions for accessing parts of the
+ * translation state which deal with the possible split correctly.
+ */
class WholeTranslationState
{
protected:
@@ -50,7 +60,10 @@
uint64_t *res;
BaseTLB::Mode mode;
- /** Single translation state. */
+ /**
+ * Single translation state. We set the number of outstanding
+ * translations to one and indicate that it is not split.
+ */
WholeTranslationState(RequestPtr _req, uint8_t *_data, uint64_t *_res,
BaseTLB::Mode _mode)
: outstanding(1), isSplit(false), mainReq(_req), sreqLow(NULL),
@@ -60,7 +73,11 @@
assert(mode == BaseTLB::Read || mode == BaseTLB::Write);
}
- /** Split translation state. */
+ /**
+ * Split translation state. We copy all state into this class, set the
+ * number of outstanding translations to two and then mark this as a
+ * split translation.
+ */
WholeTranslationState(RequestPtr _req, RequestPtr _sreqLow,
RequestPtr _sreqHigh, uint8_t *_data, uint64_t *_res,
BaseTLB::Mode _mode)
@@ -71,6 +88,13 @@
assert(mode == BaseTLB::Read || mode == BaseTLB::Write);
}
+ /**
+ * Finish part of a translation. If there is only one request then this
+ * translation is completed. If the request has been split in two then
+ * the outstanding count determines whether the translation is complete.
+ * In this case, flags from the split request are copied to the main
+ * request to make it easier to access them later on.
+ */
bool
finish(Fault fault, int index)
{
@@ -89,6 +113,10 @@
return outstanding == 0;
}
+ /**
+ * Determine whether this translation produced a fault. Both parts of the
+ * translation must be checked if this is a split translation.
+ */
Fault
getFault() const
{
@@ -102,36 +130,54 @@
return NoFault;
}
+ /** Remove all faults from the translation. */
void
setNoFault()
{
faults[0] = faults[1] = NoFault;
}
+ /**
+ * Check if this request is uncacheable. We only need to check the main
+ * request because the flags will have been copied here on a split
+ * translation.
+ */
bool
isUncacheable() const
{
return mainReq->isUncacheable();
}
+ /**
+ * Check if this request is a prefetch. We only need to check the main
+ * request because the flags will have been copied here on a split
+ * translation.
+ */
bool
isPrefetch() const
{
return mainReq->isPrefetch();
}
+ /** Get the physical address of this request. */
Addr
getPaddr() const
{
return mainReq->getPaddr();
}
+ /**
+ * Get the flags associated with this request. We only need to access
+ * the main request because the flags will have been copied here on a
+ * split translation.
+ */
unsigned
getFlags()
{
return mainReq->getFlags();
}
+ /** Delete all requests that make up this translation. */
void
deleteReqs()
{
@@ -143,6 +189,16 @@
}
};
+
+/**
+ * This class represents part of a data address translation. All state for
+ * the translation is held in WholeTranslationState (above). Therefore this
+ * class does not need to know whether the translation is split or not. The
+ * index variable determines this but is simply passed on to the state class.
+ * When this part of the translation is completed, finish is called. If the
+ * translation state class indicate that the whole translation is complete
+ * then the execution context is informed.
+ */
template <class ExecContext>
class DataTranslation : public BaseTLB::Translation
{
@@ -163,6 +219,10 @@
{
}
+ /**
+ * Finish this part of the translation and indicate that the whole
+ * translation is complete if the state says so.
+ */
void
finish(Fault fault, RequestPtr req, ThreadContext *tc,
BaseTLB::Mode mode)
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