exercises/01 fails when run in docker against ibex

[PhilDay-CT]

As noted at the Sonata Hackathon exercise/01.compartmentalisation doesn't run in the dev docker, although it does work if compiled and run on the Sonata board. I tested against the latest commit (771f2bb - Jun 3rd) in case any of the recent changes to the dev contained had fixed it, but it still fails for me.

Digging in a little the line that fails in Ibex is generating the secret in secret.cc

    secret = static_cast<int32_t>(rdcycle64());

Replacing this with, for example, makes everything run fine

    //secret = static_cast<int32_t>(rdcycle64());
    secret=666;	

Commenting out the code in secret.cc which waits for the uart (so the call to rdcycle64() is in effect the first call in the therad) also makes no difference.

Adding a compartment_error_handler() gives the error as:

JavaScript compartment: Detected PermitAccessSystemRegistersViolation(0x18).  Register PCC(0x20) contained invalid value: 0x2004ba08 (v:0 0x2004a7c0-0x2004cb40 l:0x2380 o:0x0 p: G R-cgm- X- ---)

Calling rdcycle64() in any of the examples with IBEX works fine, so I'm assuming there is some difference in the build that I'm missing, but the only thing I spotted is that exercise xmake.luna has:

option("board")
    set_default("ibex-safe-simulator")

whereas the examples use

option("board")
    set_default("sail")

I'm happy to dig further if someone can point me in the right direction.

[davidchisnall]

If the board is sail then they're not using the Ibex simulator, they're the instruction simulator generated from the Sail formal model.

[davidchisnall]

I suspect that the recent(ish) changes to the AccessSystemRegisters permissions in Ibex may have broken mcycleh access. The test suite uses mcycle but not mcycleh (it doesn't run long enough to overflow a 32-bit cycle counter. @kliuMsft, can you check?

[PhilDay-CT]

If the board is sail then they're not using the Ibex simulator, they're the instruction simulator generated from the Sail formal model.

Ah, Ok thanks. I tried changing one of the examples to the ibex simulator and then doing "xmake config --sdk=/cheriot-tools/; xmake clean; xmake; xmake run" - but that didn't fail which made me think this was the wrong track. Looks like I need to "rm -rf .xmake .cache" to really get back to a clean state ?

And the exercise needs the simulator because the sail model doesn't have a uart - is that right ?

(Sorry for the questions - still feeling my way around here some)

[davidchisnall]

You shouldn't need it, but sometimes rm -rf .xmake build is necessary.

[davidchisnall]

And the exercise needs the simulator because the sail model doesn't have a uart - is that right ?

The Sail UART is output only, yes.

[davidchisnall]

Kunyan confirms that this is an Ibex bug. The refactoring of the PermitAccessSystemRegisters logic accidentally missed mcycleh.

[davidchisnall]

The dev container is updated with the fix so this should work now.

[PhilDay-CT]

Yep - runs fine now, thanks