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Having SIGSEGV when setting serial port name

  • First of all, sorry if my English is not very comprehensive, it's a little bit rusty, and if I made some error while describing my problem, it's my first post here.

    I'm having trouble when I try to execute the following method:


    The debugger returns a SIGSEGV error, and when I enter the function that contains the error I get the following error line:

    0x64781f02  <+0x0004>        8b 59 04                 mov    0x4(%ecx),%ebx

    Header file:

    #ifndef SERIAL_H
    #define SERIAL_H
    #include <QtCore>
    #include <QString>
    #include <QSerialPort>
    class Serial : public QObject
        QMutex mutex;
        bool isConnected();
        bool serialConnect();
        bool setup();
        bool send(QString);
        bool connected;
        QString receive();
        void closeConnection();
        void serialReceived(QString);
    private slots:
        void onSerialReceived();
    #endif // SERIAL_H

    Source file:

    static QSerialPort *serialPort;
        connected = false;
    bool Serial::serialConnect()
        foreach (const QSerialPortInfo &devinfo, QSerialPortInfo::availablePorts()) {
            QSerialPort devSerial;
            if(devSerial.open(QIODevice::ReadWrite)) {
                if(devinfo.description() == "Arduino Uno" && devinfo.manufacturer() == "Arduino LLC (www.arduino.cc)") {
                    QString port = devinfo.portName();
                    qDebug() << "Serial found: " << port;
                    serialPort->setPortName(port);         //This is where I get the error
                    if(setup()) {
                        qDebug() << "Setup completed.";
                        connected = true;
                        connect(serialPort, SIGNAL(readyRead()), this, SLOT(onSerialReceived()));
                        return true;
                    }else {
                        qDebug() << "Setup failed.";
                        return false;
    bool Serial::setup()
        try {
                qDebug() << "Can't open serialport";
                return false;
            return true;
        } catch (QException e) {
            return false;

    QSerialPort source (if needed):

    /        Function: QSerialPort::QSerialPort(QObject*)
    0x64781eee  <+0x0038>        c7 43 08 00 00 00 00     movl   $0x0,0x8(%ebx)
    0x64781ef5  <+0x003f>        83 c4 14                 add    $0x14,%esp
    0x64781ef8  <+0x0042>        5b                       pop    %ebx
    0x64781ef9  <+0x0043>        5e                       pop    %esi
    0x64781efa  <+0x0044>        c2 04 00                 ret    $0x4
            Function: _ZN11QSerialPortC2EP7QObject
    0x64781efd  <+0x0047>        90                       nop
            Function: QSerialPort::setPortName(QString const&)
    0x64781efe                   53                       push   %ebx
    0x64781eff  <+0x0001>        83 ec 28                 sub    $0x28,%esp
    0x64781f02  <+0x0004>        8b 59 04                 mov    0x4(%ecx),%ebx      //Error presents in this line
    0x64781f05  <+0x0007>        8d 44 24 1c              lea    0x1c(%esp),%eax
    0x64781f09  <+0x000b>        8b 54 24 30              mov    0x30(%esp),%edx
    0x64781f0d  <+0x000f>        89 54 24 04              mov    %edx,0x4(%esp)
    0x64781f11  <+0x0013>        89 04 24                 mov    %eax,(%esp)
    0x64781f14  <+0x0016>        e8 57 53 00 00           call   0x64787270 <QSerialPortInfoPrivate::portNameToSystemLocation(QString const&)>
    0x64781f19  <+0x001b>        8b 83 9c 00 00 00        mov    0x9c(%ebx),%eax
    0x64781f1f  <+0x0021>        8b 54 24 1c              mov    0x1c(%esp),%edx
    0x64781f23  <+0x0025>        89 93 9c 00 00 00        mov    %edx,0x9c(%ebx)
    0x64781f29  <+0x002b>        89 44 24 1c              mov    %eax,0x1c(%esp)
    0x64781f2d  <+0x002f>        89 c2                    mov    %eax,%edx
    0x64781f2f  <+0x0031>        8b 00                    mov    (%eax),%eax
    0x64781f31  <+0x0033>        85 c0                    test   %eax,%eax
    0x64781f33  <+0x0035>        74 16                    je     0x64781f4b <QSerialPort::setPortName(QString const&)+77>
    0x64781f35  <+0x0037>        83 f8 ff                 cmp    $0xffffffff,%eax
    0x64781f38  <+0x003a>        74 18                    je     0x64781f52 <QSerialPort::setPortName(QString const&)+84>
    0x64781f3a  <+0x003c>        b8 ff ff ff ff           mov    $0xffffffff,%eax
    0x64781f3f  <+0x0041>        f0 0f c1 02              lock xadd %eax,(%edx)
    0x64781f43  <+0x0045>        83 f8 01                 cmp    $0x1,%eax
    0x64781f46  <+0x0048>        0f 95 c0                 setne  %al
    0x64781f49  <+0x004b>        eb 0c                    jmp    0x64781f57 <QSerialPort::setPortName(QString const&)+89>
    0x64781f4b  <+0x004d>        b8 00 00 00 00           mov    $0x0,%eax
    0x64781f50  <+0x0052>        eb 05                    jmp    0x64781f57 <QSerialPort::setPortName(QString const&)+89>
    0x64781f52  <+0x0054>        b8 01 00 00 00           mov    $0x1,%eax
    0x64781f57  <+0x0059>        84 c0                    test   %al,%al
    0x64781f59  <+0x005b>        75 1d                    jne    0x64781f78 <QSerialPort::setPortName(QString const&)+122>
    0x64781f5b  <+0x005d>        c7 44 24 08 04 00 00 00  movl   $0x4,0x8(%esp)
    0x64781f63  <+0x0065>        c7 44 24 04 02 00 00 00  movl   $0x2,0x4(%esp)

    If somebody can give me a help on this I would appreciate, thanks in advance.

  • @cesar93

    static QSerialPort *serialPort;

    That gives you a NULL serialPort. Where do you actually create/new it, before you get to the line:

    serialPort->setPortName(port);         //This is where I get the error


  • Thanks for the quickly reply,

    It was working before, I guess that when I added a piece of code to it I must have erased the part where I initialized the serialPort, already get it to work again, thanks.

  • Lifetime Qt Champion

    @cesar93 so if your problem is solved, please mark this topic as SOLVED too. Thanks