When the label begins with "IMS", why does logcat not print the log?

When the label is “IMS" At the beginning , Why? Logcat Don't print logs ?

One 、 Problem description

Why? Logcat With IMS" At the beginning Logcat Don't print logs ?

@Override
public void onClick(View v) {
    
    switch (v.getId()) {
    
        case R.id.btnOne:
            System.out.println("Button One log by sout");
            Log.e("IMSfsadfasdfasdf", "log by Log.e()");
            break;
        case R.id.btnTwo:
            System.out.println("Button Two log by sout");
            Log.e("MService", "log by Log.e()");
            break;
    }
}

journal :

04-07 15:05:48.838 4363-4363/com.licheedev.myapplication I/System.out:
Button One log by sout 04-07 15:05:49.916
4363-4363/com.licheedev.myapplication I/System.out: Button Two log by
sout 04-07 15:05:49.916 4363-4363/com.licheedev.myapplication
E/MService: log by Log.e() 04-07 15:05:54.109
4363-4363/com.licheedev.myapplication I/System.out: Button Two log by
sout 04-07 15:05:54.109 4363-4363/com.licheedev.myapplication
E/MService: log by Log.e() 04-07 15:05:54.822
4363-4363/com.licheedev.myapplication I/System.out: Button One log by
sout 04-07 15:05:55.638 4363-4363/com.licheedev.myapplication
I/System.out: Button One log by sout

Two 、 analysis

Android This line of code in the logging mechanism of . This is in function __android_log_write(prio, tag, buf);

/* XXX: This needs to go! */
if (!strcmp(tag, "HTC_RIL") ||
    !strncmp(tag, "RIL", 3) || /* Any log tag with "RIL" as the prefix */
    !strncmp(tag, "IMS", 3) || /* Any log tag with "IMS" as the prefix */
    !strcmp(tag, "AT") ||
    !strcmp(tag, "GSM") ||
    !strcmp(tag, "STK") ||
    !strcmp(tag, "CDMA") ||
    !strcmp(tag, "PHONE") ||
    !strcmp(tag, "SMS")) {
    
        log_id = LOG_ID_RADIO;
        // Inform third party apps/ril/radio.. to use Rlog or RLOG
        snprintf(tmp_tag, sizeof(tmp_tag), "use-Rlog/RLOG-%s", tag);
        tag = tmp_tag;
}

Function determines the legitimacy of the incoming parameter , After processing , Package and pass the parameters to the structure iovec, At the same time bugID, And packed iovec Pass as parameter to write_to_log.

Pay a little attention , If tag contain HTC_RIL, RIL, IMS, AT, GSM, STK, CDMA, PHONE, SMS, （ These are all related to radio）, will bugID Set to LOG_ID_RADIO. Assign different types to different buffers .

3、 ... and 、 terms of settlement ：

Method 1 ：
app Change printing in log Of TAG, Avoid these characters ：HTC_RIL, RIL, IMS, AT, GSM, STK, CDMA, PHONE, SMS

Method 2 ：
Use radio log You can see the corresponding log：

 Grab Android RIL layer  log, In the debug Android Communication code , This Log It's critical . The grab command is as follows ：

adb logcat -b radio >e://radio.log