Flash operations support by eulerdisk · Pull Request #172 · daniel5151/gdbstub

eulerdisk · 2025-05-29T20:22:13Z

Description

This PR adds support for the flash commands as described in (https://sourceware.org/gdb/current/onlinedocs/gdb.html/Packets.html#Packets).

I had to change the memory map in the armv4t example providing a real memory map, otherwise GDB would not load a real .elf file. It doesn't have to be a real memory map, but you need at least a region marked a flash containing the address of the elf sections to be loaded. (eg: .vector_table, .text etc..)
Tell me if I have to revert that, but in that case the flash commands cannot be tested.

API Stability

This PR does not require a breaking API change

Checklist

Documentation
- Ensured any public-facing rustdoc formatting looks good (via cargo doc)
- (if appropriate) Added feature to "Debugging Features" in README.md
Validation
- Included output of running examples/armv4t with RUST_LOG=trace + any relevant GDB output under the "Validation" section below
- Included output of running ./example_no_std/check_size.sh before/after changes under the "Validation" section below
If implementing a new protocol extension IDET
- Included a basic sample implementation in examples/armv4t
- IDET can be optimized out (confirmed via ./example_no_std/check_size.sh)

Validation

GDB output

[remote] Sending packet: $vFlashErase:08000000,00004000#c6
[remote] Packet received: OK
Loading section .vector_table, size 0x400 lma 0x8000000
[remote] Sending packet: $vFlashWrite:8000000:\000\000\001 \001\004\000\bO\004\000\bW\004\000\bO\004\000\bO\004\000\bO\004\000\b\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000O\004\000\bO\004\000\b\000\000\000\000O\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000\bO\004\000 [536 bytes omitted]
[remote] Packet received: OK
Loading section .text, size 0x58 lma 0x8000400
[remote] Sending packet: $vFlashWrite:8000400:\000&\bH\tI\000"\201B\001\004\aH\aI\bJ\201B\002\b\b\000\013\000\000\000\000 \000\000\000 \000\000\000 \000\000\000 X\004\000\b\200oF\000\000\200oF\000\003pG\000pG#84
[remote] Packet received: OK
[remote] Sending packet: $vFlashDone#ea
[remote] Packet received: OK

The ouput shows the loading of this simple rust program compiled for thumbv7m-none-eabi:

#![no_std]
#![no_main]

// pick a panicking behavior
use panic_halt as _; // you can put a breakpoint on `rust_begin_unwind` to catch panics
// use panic_abort as _; // requires nightly
// use panic_itm as _; // logs messages over ITM; requires ITM support
// use panic_semihosting as _; // logs messages to the host stderr; requires a debugger

use cortex_m::asm;
use cortex_m_rt::entry;

#[entry]
fn main() -> ! {
    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code

    loop {
        // your code goes here
    }
}

armv4t output

!!!!! EXAMPLE OUTPUT !!!!!

TRACE gdbstub::protocol::recv_packet     > <-- $vFlashErase:08000000,00004000#c6
 TRACE gdbstub::protocol::response_writer > --> $OK#9a
 TRACE gdbstub::protocol::recv_packet     > <-- $vFlashWrite:8000000:#f4
 TRACE gdbstub::protocol::response_writer > --> $OK#9a
 TRACE gdbstub::protocol::recv_packet     > <-- $vFlashWrite:8000400:�&H        I"�B����HJ�B����
                                                                                                ��    ��oF����oF������pG�pG��#84
 TRACE gdbstub::protocol::response_writer > --> $OK#9a
 TRACE gdbstub::protocol::recv_packet     > <-- $vFlashDone#ea
 TRACE gdbstub::protocol::response_writer > --> $OK#9a

Before/After `./example_no_std/check_size.sh` output

Before


target/release/gdbstub-nostd  :
section               size    addr
.interp                 83     792
.note.gnu.property      32     880
.note.ABI-tag           32     912
.hash                   80     944
.gnu.hash               36    1024
.dynsym                360    1064
.dynstr                266    1424
.gnu.version            30    1690
.gnu.version_r          64    1720
.rela.dyn              408    1784
.init                   27    4096
.plt                    16    4128
.plt.got                 8    4144
.text                16146    4160
.fini                   13   20308
.rodata                954   20480
.eh_frame_hdr          276   21436
.eh_frame             1396   21712
.init_array              8   28040
.fini_array              8   28048
.dynamic               480   28056
.got                   136   28536
.data                    8   28672
.bss                     8   28680
.comment                80       0
Total                20955

After


target/release/gdbstub-nostd  :
section               size    addr
.interp                 83     792
.note.gnu.property      32     880
.note.ABI-tag           32     912
.hash                   80     944
.gnu.hash               36    1024
.dynsym                360    1064
.dynstr                266    1424
.gnu.version            30    1690
.gnu.version_r          64    1720
.rela.dyn              408    1784
.init                   27    4096
.plt                    16    4128
.plt.got                 8    4144
.text                16146    4160
.fini                   13   20308
.rodata                954   20480
.eh_frame_hdr          276   21436
.eh_frame             1396   21712
.init_array              8   28040
.fini_array              8   28048
.dynamic               480   28056
.got                   136   28536
.data                    8   28672
.bss                     8   28680
.comment                80       0
Total                20955

daniel5151 · 2025-05-30T00:18:03Z

Very cool, thanks for sending this in!

From my quick skim - this looks like a straightforward, simple, non-API-breaking gdbstub extension, so I don't expect much back/forth on the PR. Looks like clippy is complaining, but once that's resolved, I'll carve out some time to review + merge it.

One thing to note: I'm currently out travelling, so even once this PR lands, I likely won't be able to cut a new release of gdbstub until those are wrapped up (ETA ~2 weeks).

daniel5151

A bit of feedback wrt. docs, but code-wise, everything is looking great.

examples/armv4t/gdb/memory_map.rs

examples/armv4t/gdb/flash.rs

src/target/ext/flash.rs

…ands

daniel5151 · 2025-06-12T13:15:31Z

Apologies for the delay.
This looks good to me!

I will push out a new gdbstub release with this protocol extension shortly

This PR adds support for the flash commands as described in (https://sourceware.org/gdb/current/onlinedocs/gdb.html/Packets.html#Packets). I had to change the memory map in the armv4t example providing a real memory map, otherwise GDB would not load a real .elf file. It doesn't have to be a real memory map, but you need at least a region marked a flash containing the address of the elf sections to be loaded. (eg: .vector_table, .text etc..)

daniel5151 · 2025-06-12T13:28:15Z

gdbstub 0.7.6 has been published to crates.io, and includes this feature.

Thank you for your contribution!

eulerdisk added 3 commits May 28, 2025 20:07

feat(flash_commands): provide flash operations for the target

be29d95

feat(flash_commands): update README

f89c6a2

feat(flash_commands): updated example armv4t

21acf1d

eulerdisk mentioned this pull request May 30, 2025

Support gdb load command probe-rs/probe-rs#3394

Merged

feat(flash_commands): fix clippy issues

338d1b2

eulerdisk force-pushed the flash_commands branch from 76cb4be to 338d1b2 Compare June 3, 2025 19:35

daniel5151 reviewed Jun 5, 2025

View reviewed changes

examples/armv4t/gdb/memory_map.rs Outdated Show resolved Hide resolved

examples/armv4t/gdb/flash.rs Show resolved Hide resolved

examples/armv4t/gdb/flash.rs Outdated Show resolved Hide resolved

src/target/ext/flash.rs Outdated Show resolved Hide resolved

feat(flash_commands): improved docs and armv4t logging for flash comm…

fbdefa0

…ands

daniel5151 merged commit 363bdd2 into daniel5151:master Jun 12, 2025
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Flash operations support#172

Flash operations support#172
daniel5151 merged 5 commits intodaniel5151:masterfrom
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Description

API Stability

Checklist

Validation

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eulerdisk commented May 29, 2025 •

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