hangs and unstable cycle counts

litex-hub / linux-on-litex-rocket

Run 64-bit Linux on LiteX + RocketChip

BSD 2-Clause "Simplified" License

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hangs and unstable cycle counts #6

Closed monniaux closed 3 years ago

monniaux commented 3 years ago

Running some test code. Sometimes the programs (which work perfectly under simulators; including GNU make, a version of the OCaml runtime…) seem to hang (control-C exits though).

Also, when they don't hang, they seem to be randomly affected by some delays leading to high cycle counts.

Could there be that sometimes accesses to the SD card fail and hang programs?

gsomlo commented 3 years ago

On Thu, Jan 14, 2021 at 12:36:56PM -0800, David Monniaux wrote:

Could there be that sometimes accesses to the SD card fail and hang programs?

Yes. SD card support (mainly the Linux litex_mmc driver, but also to an extent the LiteSDCard gateware itself) is still a work in progress.

At the moment, at least when using 64-bit Linux and LiteX + Rocket, there are data and DMA timeouts, and only single-block transfers are enabled in the Linux driver.

I'm in the process of tracking down the source of those bottlenecks, so things should improve, hopefully soon.

enjoy-digital commented 3 years ago

Thanks @monniaux, would you mind sharing your test? We could use it as an additionnal stress test while looking at the other SDCard issues.

gsomlo commented 3 years ago

LiteSDCard is now working fine, so I'm going to close this.

@monniaux -- please feel free to (re-)open this or a new issue if you're still experiencing any trouble.