Arduino 1.5, avrdude timeout if using String reserve()

Development Tools IDE 1.x
1

So weird, Arduino Mega 2560 and when I added reserve() to my code arduino starts uploading the sketch (tx/rx lights blinking away for a little while), then stops with a timeout error. If I comment those reserve lines out, no problem. My sketch size is less than 1/4 of the allowed max so it's not too large. Is there a max time to actually upload though before it times out based on time itself? Is there something especially nefarious about using reserve() ?

String line1 = "";
String line2 = "";
line1.reserve(16);
line2.reserve(16);

timeout message when reserve() not commented out:

avrdude: stk500v2_ReceiveMessage(): timeout
2

You have very likely crossed paths with the !!! bootloader bug. If that is the case, you will have to update the bootloader on your board.

3

I saw something about that earlier today. I don't have "!!!" anywhere in my code. Any links for me so I can read more to see if you're right?

4

Turn on verbose output for uploads. Search for three 21s in a row.

5

Actually, it seems that I'm running into this issue (bug with relaxation on mega2560 - Suggestions for the Arduino Project - Arduino Forum), not the !!! one. Trying to learn more about it now.

There's nothing wrong with F() or reserve(), it's just me reaching a program size limit (due to bug mentioned above).

Also, even when I shorten my progmem strings F("foo bar foobar foo") to F("fBar") for example, it sneaks past the compiler 'cause I'm squeezing JUST under the limit. When I comment out all my F()'s the program size goes from 65,674 to 49,076 bytes and. Crappy thing is the advertised limit of the Mega 2560 is 258,048 bytes

I'm using Arduino IDE 1.05, FYI.

6

Here's a great explanation of the problem and a very short sketch (search for the word 'isolation' in this thread) to reproduce the problem on a Mega2560 with Arduino 1.0.5:
http://forum.arduino.cc/index.php?topic=181233.0

7

This (and the thread you referenced above) indicates a newer toolchain solves the problem...
https://code.google.com/p/arduino/issues/detail?id=729#c3

If you are running Windows I suggest trying the toolchain from Atmel.