closures are also a kind of function pointer (not sure whether Rust has them tbh)
That's a bit out of my Rust knowledge, but normally a vtable is basically an array of function pointers that is usually stored as a global (for virtual functions in C++ for example). Calling a method from a vtable means doing an indirect call (as you're not directly calling the function, but loading the function address from the vtable and calling the function through that).
Again, the compiler will try to optimize the vtable away if possible, which may definitely happen in small programs
You could try looking at the disassembly, if you have any experience with that.
Yep, I just ran into the same problem. When trying to
clone a Waker, which calls a function defined in a manual VTable, my Arduino just crashes and doesn't respond.
@aykevl maybe you could ping @dylanmckay for tips on where to look to emit the right assembly?
I'm having trouble building though, issues with avr-gcc.
It seems like there avr-gcc flags being set that aren't supported by the one I have installed. Any ideas how to configure how avr-gcc gets called?
error: linking with `avr-gcc` failed: exit code: 1
|
= note: "avr-gcc" "-Os" "-mmcu=atmega328p" "-Wl,--eh-frame-hdr" "-L" "/home/jonah/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/avr-atmega328p/lib" "/run/media/jonah/data/Projects/smart-plug/target/avr-atmega328p/release/deps/smart_plug-12f5bd55c8f99728.smart_plug.davrc7f1-cgu.0.rcgu.o" "-o" "/run/media/jonah/data/Projects/smart-plug/target/avr-atmega328p/release/deps/smart_plug-12f5bd55c8f99728.elf" "-Wl,--gc-sections" "-L" "/run/media/jonah/data/Projects/smart-plug/target/avr-atmega328p/release/deps" "-L" "/run/media/jonah/data/Projects/smart-plug/target/release/deps" "-L" "/home/jonah/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/avr-atmega328p/lib" "-Wl,--start-group" "-Wl,--end-group" "-Wl,-Bstatic" "/run/media/jonah/data/Projects/smart-plug/target/avr-atmega328p/release/deps/libcompiler_builtins-3056cbb15200d16d.rlib" "-Wl,-Bdynamic" "-Wl,--gc-sections"
= note: /home/jonah/Downloads/avr8-gnu-toolchain-3.6.2.1759-linux.any.x86_64/avr8-gnu-toolchain-linux_x86_64/bin/../lib/gcc/avr/5.4.0/../../../../avr/bin/ld: unrecognized option '--eh-frame-hdr'
/home/jonah/Downloads/avr8-gnu-toolchain-3.6.2.1759-linux.any.x86_64/avr8-gnu-toolchain-linux_x86_64/bin/../lib/gcc/avr/5.4.0/../../../../avr/bin/ld: use the --help option for usage information
collect2: error: ld returned 1 exit status
I guess ld binutils version 2.34
@davidlenfesty What platform are you on, how did you install avr-gcc?
pacman -S avr-gcc
So I looked at the rust source tree, and traced back to the option that enables disables that flag
last link is the line that says it's false
Maybe it's time to file a ticket on the Rust repo.
a rustup update fixed the issue
And looking at my command history I didn't update until after the first time, so that was definitely it.
@jonahbron
@davidlenfesty I'm still having the same issue :(
rustup update gave me version
rustc 1.47.0-nightly (d6953df14 2020-07-25)
But I still get
unrecognized option '--eh-frame-hdr'
Eyyy found the problem, I had it in my avr-atmega328p.json file.
Getting a fresh copy from Rahix's avr-hal repo fixed it. https://github.com/Rahix/avr-hal/blob/master/chips/atmega328p-hal/avr-atmega328p.json
https://github.com/shepmaster/rust-arduino-blink-led-no-core-with-cargo/blob/a6bfaff51f97fef2d2d13c8358a9f550c2c54ece/interrupt_vector.S
How are processor-specific APIs like this going to be shared? Can they somehow be bundled with a crate?
How are processor-specific APIs like this going to be shared? Can they somehow be bundled with a crate?
however, it could do something similar to what the ruduino crate does now: inspect the target processor, then generate that code at runtime and compile it in
Although, my code is kind of a special case for when you want to write all the device code without any C
Also just a note that http://packs.download.atmel.com/ exists, where you can download interrupt vectors (and much, much more) in machine readable format. I use it in TinyGo to generate register access packages, interrupt vector code and linker script fragments for setting the memory size.
I haven't seen it often so just mention it again so people are aware that it exists.