compression helps us reduce the amount of data we have to
shuttle between the hardware interface and the rest of the world.
It takes more samples from the TRNG and represents them in a compressed
form that effectively increases the bits per byte of entropy. It
does not increase the *rate* of entropy generation -- while each
byte has more entropy, the bytes come proportionally slower. However,
this is a reasonable trade-off because kernel space calls to fetch
the entropy feed are expensive, and what this does is effectively
amortize the price of a syscall: the time per syscall is longer,
but you get more entropy out per syscall, thus effectively reducing
the needed overhead to get a certain amount of entropy.
turns out that you *have* to enable the endpoints after your
address has been assigned. You can't do it before.
Very subtle one-liner in the docs that I missed until now. :-/
this is an actually usable driver for end applications.
maybe some massaging needs to be done on shared resources, but
from the i2c standpoint this can do SMB, I2C transactions with
a fairly "normal" API.
this works by blowing apart the structure and re-assembling
it on the other side. The reason we can't simply pass it
is because the hardware pointer to the core register violates
a Rust safety rule, but Rust doesn't know that this pointer
points to a hardware register that's immutable and static versus
a regular block of memory that can go away.
this API has the unfortunate problem that only one process
can manage all the IRQs for all the serial ports, due to the
concentration of all IRQs into a single register bank.
That being said, it does support registering multiple repsonders
in a somewhat ergonomic fashion.
UDMA Rx busy bit seems to get stuck occassionally. This seems
to be aggravated if we insert a dcache_flush in the poll loop.
The current time-out code seems to mitigate the problem, but
I have low confidencne that this is a 100% solution. I have a feeling
we'll be revisiting this again soon.
- need to be able to specify the mode that a SPIM could be in
that was set up by the bootloader
- make yield() optional - it could be useful if the API is used
in userland contexts, but in an interrupt context (e.g. swapper)
it should not be used.
