I'm using SDCC to develop code for a Silabs C8051F120. I'm not a C runtime guru so I could use some advice on the following questions:

My code was fine until I included string.h.
Now the linker thinks that main needs to link to _vSerialISR. Why? And why doesn't it matter when it can't find it?

Why do I need to implement putchar just to be able to use sprintf ?

-Bill

Including any string handling stuff is going to drag in a lot of functions, but I don't know why the serial ISR would be one of them.

Are you using the pre-built libraries? Try building the libraries yourself afresh.