URL:
<
https://savannah.nongnu.org/bugs/?59089>
Summary: Optimisation of vj_uncompress_tcp breaks PPP
Project: lwIP - A Lightweight TCP/IP stack
Submitted by: ashesman
Submitted on: Thu 10 Sep 2020 12:28:23 AM UTC
Category: PPP
Severity: 3 - Normal
Item Group: Faulty Behaviour
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
lwIP version: 2.1.1
_______________________________________________________
Details:
Context: Embedded project, STM32H7, GCC Arm V9, using PPP to communicate with
a ublox Nina W152 WiFi module. Lwip V2.1.2.
We have the need to build our code size optimised (-Os). We use a debug build
(Og) and a release build with Os. We have had very robust and reliable
communications on debug build. Unfortunately since building a release build,
the PPP connection to the module seemed unstable and erratic and
communications was unreliable.
After several days of debugging it was traced down to a single function
vj_uncompress_tcp in vj.c. By disabling size optimisation of just this
function (leaving it at Og). communications is excellent. Compiling this
function with Os breaks communication. This is completely repeatable.
I have not delved into exactly what happens inside this function causing it to
become an issue.
To fix the problem (when the entire project is built with Os):
#pragma GCC push_options
#pragma GCC optimize ("Og")
int
vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
{
...
}
#pragma GCC pop_options
For now we have disabled VJ_SUPPORT in lwipopts.h as was not really required
for this use case anyway.
_______________________________________________________
Reply to this item at:
<
https://savannah.nongnu.org/bugs/?59089>
_______________________________________________
Message sent via Savannah
https://savannah.nongnu.org/_______________________________________________
lwip-devel mailing list
[hidden email]
https://lists.nongnu.org/mailman/listinfo/lwip-devel
Locked
