APS updates #2528
APS updates #2528
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These are some minor updates from walking through the session myself. * Add some context to the `entry.S` slide, which is otherwise a bit terrifying for someone who does not speak ARM assembly. * Include a simple, fake example of MMIO. * Add a "Using It" section to the minimal UART segment, parallel to the better UART * Better explanation of the `unwrap` calls in the logging example. Unwrap is never "unsafe", so remove that word. * Allow dead code in some `.rs` files. * Remove redundant warning about use of memory before MMU setup. * Rephase text about buddy-system * Fix lint warning in spin slide.
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| @@ -8,6 +8,10 @@ Before we can start running Rust code, we need to do some initialisation. | |||
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| This code is in `src/bare-metal/aps/examples/entry.S`. It's not necessary to | |||
| understand this in detail -- the takeaway is that typically some low-level setup | |||
| is needed to meet Rust's expectations of the system. | |||
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When I'm teaching I usually walk through the initialisation here, and talk about why cache coherency issues are a problem, because that is a common mistake I've seen. If people are used to doing similar things in C then it's pretty much the same, but if they're not then I think it's important to understand.
| assert_eq!( | ||
| SOME_DEVICE_BASE_ADDRESS.add(REGISTER_OFFSET).read_volatile(), | ||
| 0xaa | ||
| ); |
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What is this example trying to demonstrate? If you're just showing how to use read_volatile and write_volatile then it doesn't need to be in a main function like this, as you're not going to compile it anyway. Adding an arbitrary offset to an equally arbitrary address probably doesn't add much either.
| # Using it | ||
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| Let's write a small program using our driver to write to the serial console, and | ||
| echo incoming bytes. |
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That's not what main_minimal does.
These are some minor updates from walking through the session myself.
entry.Sslide, which is otherwise a bit terrifying for someone who does not speak ARM assembly.unwrapcalls in the logging example. Unwrap is never "unsafe", so remove that word..rsfiles.