riscv/rocket-chip
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84 Commits

Author SHA1 Message Date
Andrew Waterman
3cbc5262ec Don't permit new acquires until the release queue is drained 
If the queue is not empty before a dirty miss, C could block D.
I haven't seen this in the wild, but it could happen because of
dirty probe responses backed up in the queue.
 2017-08-13 13:18:45 -07:00
Andrew Waterman
0190724492 Actually use the C-channel acquire-before-release queue 
oops...
 2017-08-13 13:03:35 -07:00
Andrew Waterman
7387f2a93a Don't block D-channel when handling a probe 
This is an acquire-before-release regression.
 2017-08-12 16:13:24 -07:00
Andrew Waterman
604abd5b07 Only report ECC errors when the RAM was actually read 2017-08-12 15:28:03 -07:00
Andrew Waterman
18fb052fc9 DRY 2017-08-12 15:27:30 -07:00
Andrew Waterman
176110b6d3 Don't trigger ECC writebacks when a release is in flight 2017-08-12 15:23:57 -07:00
Andrew Waterman
809c7e8551 Don't merge stores that manifest WAW hazards 
The following sequence would drop the first store when eccBytes=4:

    sb x0, 0(t0)
    nop
    sb x0, 4(t0)
    nop
    sb x0, 1(t0)

Because the first and second store are to different ECC granules, the
hazard check correctly allowed the second one to proceed, but the third
was merged with the second, even though it conflicted with the first.
So, don't allow the third to be merged with the second, since the second
stored to a different ECC granule.
 2017-08-08 15:19:05 -07:00
Andrew Waterman
82e13443b2 Merge pull request #937 from freechipsproject/critical-paths 
Perform tag error detectoin/correction in same cycle as RAM
 2017-08-08 15:03:28 -07:00
Andrew Waterman
7935c61c19 Don't report to the DTIM that data is cacheable 
Otherwise, it will attempt to perform AMOs where they're unsupported!
 2017-08-08 11:55:04 -07:00
Andrew Waterman
74d309c18e Make I vs. D a static property of TLB, not an input pin 
The microarchitecture doesn't really support unified TLBs, so don't fake it.
 2017-08-08 11:54:47 -07:00
Andrew Waterman
e92981b0bd DRY 2017-08-08 11:46:38 -07:00
Andrew Waterman
62ccba304c Perform tag error detectoin/correction in same cycle as RAM 
The tag RAMs tend to be fast, so take up some of the slack.
This makes s2_nack faster.
 2017-08-08 10:21:30 -07:00
Andrew Waterman
402907990c Revert "Remove one gate from D$ ECC check" 
This reverts commit 7d94074b05, which
works fine with optimistic behavioral RAMs but not real ones.
 2017-08-07 17:33:20 -07:00
Andrew Waterman
7d94074b05 Remove one gate from D$ ECC check 
The D$ corrects via writeback, so which word the error was in doesn't
matter, as the entire line is corrected.
 2017-08-06 17:36:53 -07:00
Andrew Waterman
83875e3a0c Only flush D$ on FENCE.I if it won't always be probed on I$ miss 2017-08-05 14:22:40 -07:00
Andrew Waterman
991e16de92 Remove probe address mux from TLB response path 2017-08-05 12:57:38 -07:00
Andrew Waterman
2eb239d03f Add option to retime D$ way mux into subsequent pipeline stage 2017-08-01 23:59:20 -07:00
Andrew Waterman
2ecea2ef60 Don't use a pipe queue on D$ TL A-channel 
This cuts an I$->D$ path.
 2017-08-01 15:17:07 -07:00
Andrew Waterman
5681693ccc Fix a D$ ready-valid signaling regression 
I broke this in 66d06460fa.
 2017-07-31 18:05:14 -07:00
Henry Cook
11332c1226 dcache: break potential combinatorial loop by making pstore_drain_on_miss more conservative 2017-07-31 14:03:30 -07:00
Andrew Waterman
ac4339a8e7 Pass D$ backpressure to D-channel, rather than asserting 2017-07-29 11:48:36 -07:00
Andrew Waterman
edcd2c696c Avoid needless stall on E-channel back pressure 2017-07-29 11:47:58 -07:00
Andrew Waterman
2e8b02e780 Merge D$ store hits when ECC is enabled 
This avoids pipeline flushes due to subword WAW hazards, as with
consecutive byte stores.
 2017-07-28 12:56:36 -07:00
Andrew Waterman
838864870e Bypass TLB refill signal to halve L2 TLB hit time 
The 4-cycle hit time is 1 cycle too long to avoid a second
pipeline replay, so it was effectively 9 cycles instead of 4.
 2017-07-28 12:56:36 -07:00
Andrew Waterman
ae1f7a95f6 Don't nack misses when there's a pending store 
That effectively increased the miss latency by 5 cycles when there was
a store hit followed by a load miss.  Since pending stores are drained
when releaseInFlight, the check I removed was redundant.
 2017-07-28 12:56:36 -07:00
Andrew Waterman
66d06460fa Add option for acquire-before-release 2017-07-25 15:19:16 -07:00
Henry Cook
4c595d175c Refactor package hierarchy and remove legacy bus protocol implementations (#845) 
* Refactors package hierarchy.

Additionally:
  - Removes legacy ground tests and configs
  - Removes legacy bus protocol implementations
  - Removes NTiles
  - Adds devices package
  - Adds more functions to util package
 2017-07-07 10:48:16 -07:00
Andrew Waterman
be4eceec0d Fix stupid D$ probe bug 2017-07-06 01:20:47 -07:00
Andrew Waterman
90a7d6a343 Add L2 TLB option 2017-07-06 01:19:18 -07:00
Andrew Waterman
0ef45fac9b Add tag ECC to D$ 2017-07-03 18:16:37 -07:00
Andrew Waterman
e9752f76ae Improve probe state machine 
- Reduce reliance on s2_prb_ack_data due to future ECC changes
- Shave a cycle off valid, but clean, probes
- Code cleanup
 2017-07-03 16:25:04 -07:00
Richard Xia
5b46350bc3 Make sure that DCache s2_xcpt data scratchpad case is assigned to after initial assignment. 2017-06-30 17:44:16 -07:00
Wesley W. Terpstra
ca3030cba3 dcache: fix a gender inversion bug introduced in #826 2017-06-28 15:38:53 -07:00
Andrew Waterman
b9a934ae28 Support eccBytes > 1 2017-06-28 02:09:18 -07:00
Andrew Waterman
6f8fdff762 Basic L1 D$ ECC support 
Only supports ECC on data, not tags; only supports byte granularity.
 2017-06-28 02:09:18 -07:00
Andrew Waterman
6100600179 Minor D$ code cleanup 2017-06-28 02:09:18 -07:00
Andrew Waterman
8aa16a11f3 Reduce D$ access energy when refill width > access width 2017-06-28 02:09:18 -07:00
Andrew Waterman
25f585f2a9 Remove unused signal from TLB interface 2017-06-28 02:09:18 -07:00
Henry Cook
6b79842e66 dcache: just left shift by untagbits to get tag 
Always safe because of the requirement on coreplex/RocketTiles.scala:126
 2017-06-20 16:35:28 -07:00
Wesley W. Terpstra
80c63c0da6 rocket: include hartid in cache master names 2017-06-02 15:52:23 -07:00
Andrew Waterman
dbc5e7c494 Add TLB miss performance counters (#762) 2017-05-23 12:52:25 -07:00
Andrew Waterman
b2b4c1abcd Separate tag ECC and data ECC options (#761) 2017-05-23 12:51:48 -07:00
Andrew Waterman
3a1a37d41b Support PutPartial in ScratchpadSlavePort 2017-05-02 03:07:02 -07:00
Andrew Waterman
f8151ce786 Remove subword load muxing in ScratchpadSlavePort 2017-05-02 00:14:46 -07:00
Andrew Waterman
8fd5ecdff8 Set io.cpu.resp.bits.addr for MMIO loads without affecting QoR 2017-04-27 19:50:38 -07:00
Andrew Waterman
80d826b94a Make DTIM deduplicatable 2017-04-26 19:35:35 -07:00
Wesley W. Terpstra
f3ab23d068 dcache: fix stupidly wrong crossing comparison (#703) 2017-04-25 09:18:41 -07:00
Wesley W. Terpstra
4807ce7ced dcache: put a flow Q to absorb back-pressure without restarting pipeline (#701) 
* dcache: put a flow Q to absorb back-pressure without restarting pipeline

When used with a RationalCrossing, pipelined MMIO does not come out cleanly.
The first beat works, but if the second beat gets stalled, the pipeline is
restarted. This is a quick hacky test to absorb the beats. Perhaps a better
fix can be made to achieve the same effect.

* dcache: provision as few stages as possible
 2017-04-24 23:28:04 -07:00
Andrew Waterman
d82a0dc231 Mitigate D$ exception critical path, yet again 2017-04-18 00:47:58 -07:00
Andrew Waterman
c99ce7ce5d Only report D$ exceptions on not-nacked accesses 2017-04-18 00:47:58 -07:00