xDot printf is broken on mbed OS 5.5.4

[janjongboom]

#include "mbed.h"

int main() {
    Serial pc(USBTX, USBRX);
    pc.baud(115200);

    while (1) {
        pc.printf("test\n");
        wait_ms(500);
    }
}

On mbed OS 5.5.3 => normal output on serial

On mbed OS 5.5.4 => random characters on serial

[0xc0170]

cc @mfiore02

[janjongboom]

Mike has left MT. So /cc @reissjason

[janjongboom]

This issue still persists in mbed OS 5.5. Bisecting tells me that this is the culprit:

commit 254fb39
Author: jeromecoutant [email protected]
Date: Tue Jul 11 14:00:47 2017 +0200

STM32L1 : json clock source configuration

- default value is the same as before patch
- system_stm32l1xx.c file is copied to family level with all other ST cube files
- specific clock configuration is now in a new file: system_clock.c (target level)

[0xc0170]

This is the fix: #4922 ?

[janjongboom]

@0xc0170 OK cool.