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Posted to commits@nuttx.apache.org by "danielappiagyei-bc (via GitHub)" <gi...@apache.org> on 2023/09/09 20:58:01 UTC
[GitHub] [nuttx] danielappiagyei-bc opened a new issue, #10556: Segger Real Time Transfer (RTT) Usage
danielappiagyei-bc opened a new issue, #10556:
URL: https://github.com/apache/nuttx/issues/10556
Hi,
Is there any documentation or examples on how to use Segger's RTT functionality in NuttX?
I've read [segger's documentation](https://wiki.segger.com/RTT) and set the appropriate [nuttx kconfig's](https://github.com/apache/nuttx/blob/nuttx-12.2.1/drivers/segger/Kconfig):
```
CONFIG_STREAM_RTT=y
CONFIG_SEGGER_RTT=y
# IMXRT1064 cache line is 4 bytes
CONFIG_SEGGER_RTT_CPU_CACHE_LINE_SIZE=4
```
After compiling I see an `RTT` directory generated under `drivers/segger/` with segger's source and header RTT implementation files.
I include [segger/rtt.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/segger/rtt.h) in a file of mine that gets compiled **as C++** but compilation fails due to `rtt.h` using the C++ reserved keyword `public` for fields in `struct lib_rttoutstream_s` and `struct lib_rttinstream_s`. Additionally, the transitive include [streams.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h) uses `public` as well as the `this` keyword (e.g., [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L73) and [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L140)).
rtt.h uses a '#ifdef __cplusplus' guard [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/segger/rtt.h#L62) so I'm assuming including it from a c++ file was an intended use case. Could someone help me understand if this is a bug or if I'm attempting to use the RTT API incorrectly?
Thanks!
**NuttX version**: 12.2.1
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[GitHub] [nuttx] danielappiagyei-bc commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "danielappiagyei-bc (via GitHub)" <gi...@apache.org>.
danielappiagyei-bc commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712909905
> If we want to support c++ code to use stream interface, this is the correct way to fix the problem, do you have better method than rename?
Not at all! I'm new here so I just wanted to make sure I wouldn't be overstepping or breaking any rules by making such a big change. :-) Thanks!
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[GitHub] [nuttx] xiaoxiang781216 commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "xiaoxiang781216 (via GitHub)" <gi...@apache.org>.
xiaoxiang781216 commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712909101
If we want to support c++ code to use stream interface, this is the correct way to fix the problem.
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[GitHub] [nuttx] xiaoxiang781216 closed issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "xiaoxiang781216 (via GitHub)" <gi...@apache.org>.
xiaoxiang781216 closed issue #10556: Segger Real Time Transfer (RTT) Usage
URL: https://github.com/apache/nuttx/issues/10556
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[GitHub] [nuttx] danielappiagyei-bc commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "danielappiagyei-bc (via GitHub)" <gi...@apache.org>.
danielappiagyei-bc commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712907771
**RE: replacing the usage of C++ keywords from C headers**
Replacing even just `this` and `public` from https://github.com/apache/nuttx/blob/master/include/nuttx/streams.h will be a big change that touches a lot of files. That header defines a bunch of `stream` struct types that have a field named `public` (e.g., [here](https://github.com/apache/nuttx/blob/master/include/nuttx/streams.h#L140)). Therefore, any C source or header that includes stream.h and uses stream struct objects will need to be updated to use the new field name as well. I don't mind coming up with a renaming patch and submitting a PR, but I want to make sure that you all will be okay with such a big change beforehand.
Here are just a few examples I got when I:
- added the `-Wc++-compat` flag to `CFLAGS` in [IMXRT's Make.defs](https://github.com/apache/nuttx/blob/master/boards/arm/imxrt/imxrt1064-evk/scripts/Make.defs#L43)
- added `CONFIG_STREAM_RTT=y` to [IMXRT's defconfig](https://github.com/apache/nuttx/blob/master/boards/arm/imxrt/imxrt1064-evk/configs/nsh/defconfig)
- and added `#include <nuttx/segger/rtt.h>` to [nsh.h in nuttx-apps](https://github.com/apache/nuttx-apps/blob/master/nshlib/nsh.h)
```
stdio/lib_vdprintf.c:60:51: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
60 | lib_bufferedoutstream(&outstream, &rawoutstream.public);
| ^~~~~~
stdio/lib_vdprintf.c:61:33: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
61 | ret = lib_vsprintf(&outstream.public, fmt, ap);
| ^~~~~~
In file included from /home/daniel.appiagyei/projects/dan-nuttx/nuttx/libs/libc/libc.h:39,
from stdio/lib_vdprintf.c:45:
stdio/lib_vdprintf.c:62:31: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
62 | lib_stream_flush(&outstream.public);
| ^~~~~~
stdio/lib_vdprintf.c:62:31: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
62 | lib_stream_flush(&outstream.public);
| ^~~~~~
CC: stdio/lib_vsscanf.c stdio/lib_vsscanf.c: In function 'vsscanf':
stdio/lib_vsscanf.c:53:60: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
53 | n = lib_vscanf((FAR struct lib_instream_s *)&meminstream.public, NULL,
```
Is such a big change something you'd all be okay with?
> The code snippet is more like rtt syslog channel
Got it, thanks!
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[GitHub] [nuttx] danielappiagyei-bc commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "danielappiagyei-bc (via GitHub)" <gi...@apache.org>.
danielappiagyei-bc commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712709998
> it's wrong to use public(C++ keyword) in stream interface, please provide a patch to rename public to other word(e.g. common).
Should I also provide a patch for the `this` keyword being used? Also would forbidding the use of C++ keywords in C be something to add to the [C coding standard](https://nuttx.apache.org/docs/latest/contributing/coding_style.html) as well as automated checks in `nxstyle`? Not sure if this is something that should be brought up in the mailing list or not.
> 4. rtt serial console: https://github.com/apache/nuttx/pull/9777
Thanks Xiang, it looks like this is equivalent to what I was looking for. I see that this PR introduced the `SERIAL_RTT` kconfig.
This was after NuttX 12.2.1 was released so it didn't make the cut.
For posterity, I'll post a code snippet of how I was able to get RTT working in my nuttx version in a C file:
```
#include <nuttx/segger/rtt.h>
....
struct lib_rttoutstream_s out_stream = {0};
/* channel 0 is reserved by RTT for the Terminal*/
lib_rttoutstream_open(&out_stream, 0, CONFIG_SEGGER_RTT_BUFFER_SIZE_UP);
/* the below should be equivalent to `out_stream.public.puts(&out_stream.public, "dan\r\n", sizeof("dan\r\n");` */
out_stream.public.putc(&out_stream.public, (int)'d');
out_stream.public.putc(&out_stream.public, (int)'a');
out_stream.public.putc(&out_stream.public, (int)'n');
out_stream.public.putc(&out_stream.public, (int)'\r');
out_stream.public.putc(&out_stream.public, (int)'\n');
out_stream.public.putc(&out_stream.public, (int)'\0');
while (1){
usleep(500);
}
```
Using Segger's [JLinkRTTViewer](https://www.segger.com/products/debug-probes/j-link/tools/rtt-viewer/), I attached to the existing J-link debug session I had with Segger Ozone and was able to see my log in Terminal 0:
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[GitHub] [nuttx] xiaoxiang781216 commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "xiaoxiang781216 (via GitHub)" <gi...@apache.org>.
xiaoxiang781216 commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712696651
> Hi, Is there any documentation or examples on how to use Segger's RTT functionality in NuttX? I've read [segger's documentation](https://wiki.segger.com/RTT) and set the appropriate [nuttx kconfig's](https://github.com/apache/nuttx/blob/nuttx-12.2.1/drivers/segger/Kconfig):
>
> ```
> CONFIG_STREAM_RTT=y
> CONFIG_SEGGER_RTT=y
> # IMXRT1064 cache line is 4 bytes
> CONFIG_SEGGER_RTT_CPU_CACHE_LINE_SIZE=4
> ```
>
> After compiling I see an `RTT` directory generated under `drivers/segger/` with segger's source and header RTT implementation files.
In most case, you don't need use rtt stream in the code directly, rtt already integrate into various nuttx subsystem:
1. semihost(access PC file): enable CONFIG_FS_HOSTFS and ARM_SEMIHOSTING_HOSTFS, issue this command in nsh:
```
mount -t hostfs -o fs=/path/to/host /path/to/nuttx
```
2. sysview: https://github.com/apache/nuttx/issues/5843 https://github.com/apache/nuttx/issues/9991
3. thread awareness: https://github.com/apache/nuttx/issues/9200
4. rtt serial console: https://github.com/apache/nuttx/pull/9777
5. rtt syslog: https://github.com/apache/nuttx/pull/5388
> I include [segger/rtt.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/segger/rtt.h) in a file of mine that gets compiled **as C++** but compilation fails due to `rtt.h` using the C++ reserved keyword `public` for fields in `struct lib_rttoutstream_s` and `struct lib_rttinstream_s`. Additionally, the transitive include [streams.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h) uses `public` as well as the `this` keyword (e.g., [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L73) and [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L140)).
>
> rtt.h uses a '#ifdef __cplusplus' guard [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/segger/rtt.h#L62) so I'm assuming including it from a c++ file was an intended use case. Could someone help me understand if this is a bug or if I'm attempting to use the RTT API incorrectly?
>
it's wrong to use public(C++ keyword) in stream interface, please provide a patch to rename public to other word(e.g. common).
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[GitHub] [nuttx] xiaoxiang781216 commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "xiaoxiang781216 (via GitHub)" <gi...@apache.org>.
xiaoxiang781216 commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712744663
> > it's wrong to use public(C++ keyword) in stream interface, please provide a patch to rename public to other word(e.g. common).
>
> Should I also provide a patch for the `this` keyword being used?
Yes.
> Also would forbidding the use of C++ keywords in C be something to add to the [C coding standard](https://nuttx.apache.org/docs/latest/contributing/coding_style.html) as well as automated checks in `nxstyle`?
it will be great.
> Not sure if this is something that should be brought up in the mailing list or not.
>
it's a natural requirement that all c header files should be work with c++ compiler.
> > 4. rtt serial console: [Add SEGGER RTT serial/console support #9777](https://github.com/apache/nuttx/pull/9777)
>
> Thanks Xiang, it looks like this is equivalent to what I was looking for. I see that this PR introduced the `SERIAL_RTT` kconfig. This was after NuttX 12.2.1 was released so it didn't make the cut. For posterity, I'll post a code snippet of how I was able to get RTT working in my nuttx version in a C file:
>
> ```
> #include <nuttx/segger/rtt.h>
> ....
>
> struct lib_rttoutstream_s out_stream = {0};
> /* channel 0 is reserved by RTT for the Terminal*/
> lib_rttoutstream_open(&out_stream, 0, CONFIG_SEGGER_RTT_BUFFER_SIZE_UP);
>
> /* the below should be equivalent to `out_stream.public.puts(&out_stream.public, "dan\r\n", sizeof("dan\r\n");` */
> out_stream.public.putc(&out_stream.public, (int)'d');
> out_stream.public.putc(&out_stream.public, (int)'a');
> out_stream.public.putc(&out_stream.public, (int)'n');
> out_stream.public.putc(&out_stream.public, (int)'\r');
> out_stream.public.putc(&out_stream.public, (int)'\n');
> out_stream.public.putc(&out_stream.public, (int)'\0');
>
> while (1){
> usleep(500);
> }
> ```
>
The code snippet is more like rtt syslog channel:
https://github.com/apache/nuttx/blob/master/drivers/segger/syslog_rtt.c
not rtt serial device:
https://github.com/apache/nuttx/blob/master/drivers/segger/serial_rtt.c
> Using Segger's [JLinkRTTViewer](https://www.segger.com/products/debug-probes/j-link/tools/rtt-viewer/), I attached to the existing J-link debug session I had with Segger Ozone and was able to see my log in Terminal 0: 
If you just want to see the log, syslog_rtt is better than serial_rtt. The later is designed to work with nsh through JLink.
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[GitHub] [nuttx] xiaoxiang781216 commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "xiaoxiang781216 (via GitHub)" <gi...@apache.org>.
xiaoxiang781216 commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1713052670
> > do you have better method than rename?
>
> Not at all! I'm new here so I just wanted to make sure I wouldn't be overstepping or breaking any rules by making such a big change. :-) Thanks!
The change is fine since there is no the logic change, but a bunch of rename.
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[GitHub] [nuttx] danielappiagyei-bc commented on issue #10556: Segger Real Time Transfer (RTT) Usage
Posted by "danielappiagyei-bc (via GitHub)" <gi...@apache.org>.
danielappiagyei-bc commented on issue #10556:
URL: https://github.com/apache/nuttx/issues/10556#issuecomment-1712717696
> I include [segger/rtt.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/segger/rtt.h) in a file of mine that gets compiled as C++ but compilation fails due to rtt.h using the C++ reserved keyword public for fields in struct lib_rttoutstream_s and struct lib_rttinstream_s. Additionally, the transitive include [streams.h](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h) uses public as well as the this keyword (e.g., [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L73) and [here](https://github.com/apache/nuttx/blob/nuttx-12.2.1/include/nuttx/streams.h#L140)).
Following up, GCC has the [-Wc++-compat](https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wc_002b_002b-compat) warning which can catch this in the future. Below is an excerpt of what it found from the code snippet in my previous comment. I also added the following line to see if it would catch the `this` keyword: `int this = 0;`
```
gpio.c:136:9: warning: identifier 'this' conflicts with C++ keyword [-Wc++-compat]
136 | int this = 0;
| ^~~~
gpio.c:142:16: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
142 | out_stream.public.putc(&out_stream.public, (int)'d');
| ^~~~~~
gpio.c:142:40: warning: identifier 'public' conflicts with C++ keyword [-Wc++-compat]
142 | out_stream.public.putc(&out_stream.public, (int)'d');
| ^~~~~~
```
If enabling this check across all of nuttx would be too restrictive (because of other, unwanted things it warns about) then an alternative would be a shellscript which compiles nuttx with this warning enabled and greps the output for "conflicts with C++ keyword". If found then the script would exit unsuccessfully. This could be a companion to `nxstyle`.
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