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Merged
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Mar 9, 2021
Merged

Update 06 hello world to use shared cargo config #309

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8 changes: 0 additions & 8 deletions src/06-hello-world/.cargo/config
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101 changes: 21 additions & 80 deletions src/06-hello-world/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -77,95 +77,36 @@ from `/tmp` directory (on Windows `%TEMP%`) to launch OpenOCD similar as describ

Alright. Now, let's build the starter code and flash it into the microcontroller.

To avoid passing the `--target thumbv7em-none-eabihf` flag to every Cargo invocation we
have added `[build]` with a default target, `target = "thumbv7em-none-eabihf"`, to .cargo/config.
Now if `--target` is not specified `cargo` will assume that the target is `thumbv7em-none-eabihf`.

```
[target.thumbv7em-none-eabihf]
runner = "arm-none-eabi-gdb -q -x openocd.gdb"
rustflags = [
"-C", "link-arg=-Tlink.x",
]

[build]
target = "thumbv7em-none-eabihf"
```

In addition, our `opendocd.gdb` has some additional lines. Compared to the previous
section `set`'s and initialize `monitor`ing so `iprint!` and `iprintln!`
macros work and output is visible on a console. Below the contents with comments:

``` console
$ cat openocd.gdb
# Connect to gdb remote server
target remote :3333

# Load will flash the code
load

# Enable demangling asm names on disassembly
set print asm-demangle on

# Enable pretty printing
set print pretty on

# Disable style sources as the default colors can be hard to read
set style sources off

# Have the tpiu send the data to a file itm.txt
monitor tpiu config internal itm.txt uart off 8000000

# Turn on the itm port
monitor itm port 0 on

# Set a breakpoint at main
break main

# Continue running and we'll hit the main breakpoint
continue
```

We will now run the application and single step through it. Since we've added
the `monitor` commands in `openocd.gdb` OpenOCD will redirect the ITM output to
itm.txt and `itmdump` will write it to its terminal window.
We will now build and run the application, `cargo run`. And step through it using `next`.
Since `openocd.gdb` contains the `monitor` commands in `openocd.gdb` OpenOCD will redirect
the ITM output to itm.txt and `itmdump` will write it to its terminal window. Also, it setup
break points and stepped through the trampoline we are at the first executable
statement in `fn main()`:

``` console
~/embedded-discovery/src/06-hello-world
$ cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.01s
Running `arm-none-eabi-gdb -q -x openocd.gdb ~/prgs/rust/tutorial/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world`
Reading symbols from ~/prgs/rust/tutorial/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world...
0x00000000 in ?? ()
Running `arm-none-eabi-gdb -q -x ../openocd.gdb ~/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world`
Reading symbols from ~/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world...
hello_world::__cortex_m_rt_main () at ~/embedded-discovery/src/06-hello-world/src/main.rs:14
14 loop {}
Loading section .vector_table, size 0x194 lma 0x8000000
Loading section .text, size 0x28d8 lma 0x8000194
Loading section .rodata, size 0x6b8 lma 0x8002a6c
Start address 0x08000194, load size 12580
Transfer rate: 18 KB/sec, 4193 bytes/write.
Breakpoint 1 at 0x80001f0: file src/06-hello-world/src/main.rs, line 8.
Loading section .text, size 0x2828 lma 0x8000194
Loading section .rodata, size 0x638 lma 0x80029bc
Start address 0x08000194, load size 12276
Transfer rate: 18 KB/sec, 4092 bytes/write.
Breakpoint 1 at 0x80001f0: file ~/embedded-discovery/src/06-hello-world/src/main.rs, line 8.
Note: automatically using hardware breakpoints for read-only addresses.
Breakpoint 2 at 0x800092a: file /home/wink/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs, line 570.
Breakpoint 3 at 0x80029a8: file /home/wink/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs, line 560.

Breakpoint 1, hello_world::__cortex_m_rt_main_trampoline () at src/06-hello-world/src/main.rs:8
Breakpoint 1, hello_world::__cortex_m_rt_main_trampoline () at ~/embedded-discovery/src/06-hello-world/src/main.rs:8
8 #[entry]
```

We are now stopped at `#[entry]` and since, as before, it's a trampoline:
hello_world::__cortex_m_rt_main () at ~/embedded-discovery/src/06-hello-world/src/main.rs:10
10 let mut itm = aux6::init();

``` console
(gdb) disassemble /m
Dump of assembler code for function main:
8 #[entry]
0x080001ec <+0>: push {r7, lr}
0x080001ee <+2>: mov r7, sp
=> 0x080001f0 <+4>: bl 0x80001f6 <hello_world::__cortex_m_rt_main>
0x080001f4 <+8>: udf #254 ; 0xfe
```

We need to initially `step` into the main function which will position us at line 10:

``` text
(gdb) step
hello_world::__cortex_m_rt_main () at src/06-hello-world/src/main.rs:10
10 let mut itm = aux6::init();
(gdb)
```

Now issue a `next` command which will exectue `aux6::init()` and
Expand Down
26 changes: 0 additions & 26 deletions src/06-hello-world/openocd.gdb
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47 changes: 29 additions & 18 deletions src/06-hello-world/panic.md
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Original file line number Diff line number Diff line change
Expand Up @@ -22,25 +22,31 @@ define hook-quit
end
```

OK, now use `cargo run` and it stops at `#[entry]`:
OK, now use `cargo run` and it stops at the first line of `fn main()`:

``` console
$ cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.01s
Running `arm-none-eabi-gdb -q -x openocd.gdb ~/prgs/rust/tutorial/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world`
Reading symbols from ~/prgs/rust/tutorial/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world...
panic_itm::panic (info=0x20009fa0) at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs:57
57 atomic::compiler_fence(Ordering::SeqCst);
Compiling hello-world v0.2.0 (~/embedded-discovery/src/06-hello-world)
Finished dev [unoptimized + debuginfo] target(s) in 0.11s
Running `arm-none-eabi-gdb -q -x ../openocd.gdb ~/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world`
Reading symbols from ~/embedded-discovery/target/thumbv7em-none-eabihf/debug/hello-world...
hello_world::__cortex_m_rt_main () at ~/embedded-discovery/src/06-hello-world/src/main.rs:10
10 panic!("Hello, world!");
Loading section .vector_table, size 0x194 lma 0x8000000
Loading section .text, size 0x2198 lma 0x8000194
Loading section .rodata, size 0x5d8 lma 0x800232c
Start address 0x08000194, load size 10500
Transfer rate: 17 KB/sec, 3500 bytes/write.
Breakpoint 1 at 0x80001f0: file src/06-hello-world/src/main.rs, line 8.
Loading section .text, size 0x20fc lma 0x8000194
Loading section .rodata, size 0x554 lma 0x8002290
Start address 0x08000194, load size 10212
Transfer rate: 17 KB/sec, 3404 bytes/write.
Breakpoint 1 at 0x80001f0: file ~/embedded-discovery/src/06-hello-world/src/main.rs, line 8.
Note: automatically using hardware breakpoints for read-only addresses.

Breakpoint 1, hello_world::__cortex_m_rt_main_trampoline () at src/06-hello-world/src/main.rs:8
8 #[entry]
Breakpoint 2 at 0x8000222: file ~/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs, line 570.
Breakpoint 3 at 0x800227a: file ~/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs, line 560.

Breakpoint 1, hello_world::__cortex_m_rt_main_trampoline () at ~/embedded-discovery/src/06-hello-world/src/main.rs:8
8 #[entry]
hello_world::__cortex_m_rt_main () at ~/embedded-discovery/src/06-hello-world/src/main.rs:10
10 panic!("Hello, world!");
(gdb)
```

We'll use short command names to save typing, enter `c` then the `Enter` or `Return` key:
Expand Down Expand Up @@ -93,19 +99,24 @@ xPSR: 0x01000000 pc: 0x08000194 msp: 0x2000a000
(gdb) disable 1

(gdb) break rust_begin_unwind
Breakpoint 2 at 0x80010f0: file ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs, line 47.
Breakpoint 4 at 0x800106c: file ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs, line 47.

(gdb) info break
Num Type Disp Enb Address What
1 breakpoint keep n 0x080001f0 in hello_world::__cortex_m_rt_main_trampoline at src/06-hello-world/src/main.rs:8
1 breakpoint keep n 0x080001f0 in hello_world::__cortex_m_rt_main_trampoline
at ~/prgs/rust/tutorial/embedded-discovery/src/06-hello-world/src/main.rs:8
breakpoint already hit 1 time
2 breakpoint keep y 0x080010f0 in panic_itm::panic
2 breakpoint keep y 0x08000222 in cortex_m_rt::DefaultHandler_
at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs:570
3 breakpoint keep y 0x0800227a in cortex_m_rt::HardFault_
at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.13/src/lib.rs:560
4 breakpoint keep y 0x0800106c in panic_itm::panic
at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs:47

(gdb) c
Continuing.

Breakpoint 2, panic_itm::panic (info=0x20009fa0) at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs:47
Breakpoint 4, panic_itm::panic (info=0x20009fa0) at ~/.cargo/registry/src/github.com-1ecc6299db9ec823/panic-itm-0.4.2/src/lib.rs:47
47 interrupt::disable();
```

Expand Down