Bugfix for the tag cache concurrency issue

lowRISC / lowrisc-chip

The root repo for lowRISC project and FPGA demos.

http://www.lowrisc.org/

Other

596 stars 148 forks source link

Bugfix for the tag cache concurrency issue #56

Closed wsong83 closed 7 years ago

wsong83 commented 7 years ago

To handle the concurrency issue in tag cache

redesign the control logic
constrain concurrency by locking the top level line
avoid using queues to allow parallel transactions in waiting
always lock before write

wsong83 commented 7 years ago

@jrrk

There are some problems with the minion-soc. Right now, I can boot Linux on FPGA using a a bitstream from Flash and boot.bin from SD. However, I fail to mount the SD to Linux. Also if a run 'h' command in selftest, it reports sd timeout multiple times and then freeze (in hardware sense as I cannot reset using trace debugger either)!

Would you please have a look and try to fix it? Then I can have this merged to release as soon as possible.

WTB, there is no straight-forward way to run a FPGA simulation. Even I say disable the minion-sd, printf functions still go into the minion programs in the bare-metal/driver directories.

wsong83 commented 7 years ago

@jrrk Would you please have a look and verify that this PR would not affect the minion side, a.k.a. it still allows Linux to be correctly booted and SD correctly mounted. Then I think it is time to have it merged.

jrrk commented 7 years ago

I have built and installed the update branch, and there were no problems that I could see. However the Linux patches seem not to be up-to-date (there is no scrolling in the VGA terminal window). This needs investigating before the merge is finalised.

wsong83 commented 7 years ago

@jrrk Since the linux patch is now merged to minion-v0.4 in riscv-linux, I think this PR is ready to go after revert your last commit?

jrrk commented 7 years ago

It should be ready to go after one last run through Travis

wsong83 commented 7 years ago

Thanks!