Alexandru Radovici

Can you please change the list to use checkboxes? It would be easier to track.

> FWIW, this is pretty much exactly what I have envsioned on the call. IMHO a generic mechanism like this is preferable over a more specific one related to buffers...

I added the RISC-V port, @alistair23 I would love some feedback.

> @alexandruradovici I had a quick look and it looks good. Like Hudson said if there is a userspace implantation I can test and have a closer look at that...

I tried to improve the code size for RISC-V. I deleted the `debug!` message and deleted some redundant checks, it seems that the code difference is now around 640 bytes....

> FWIW, #3080 could be of interested here. I was reminded of #2582 while reviewing this and noticing your use of `volatile_` accesses. Long story short, you should not (be...

I see your point @vsukhoml, but having a *complex command* system call (allow buffer list + subscribe + command) wouldn't require also filling out a longer struct (pointer +size x...

I did some performance tests. I ran sets of 25, 50 and 100 *command* system calls to the gpio driver and led driver. The test bench works in the following...

> There are few things which makes me thing code size on caller site can grow - filling memory struct requires more instructions than just shuffling values in register, you...

I made another test [application](https://github.com/WyliodrinEmbeddedIoT/libtock-c/blob/packed_syscall_performance/examples/packed_driver/main.c) that uses all the system calls. The used [driver](https://github.com/WyliodrinEmbeddedIoT/tock/blob/packed_syscall_performance/capsules/src/packed.rs) does receives allows, a subscribe, and a command. It seems that using packed system call saves...