Fwd: printf does not work

[Christian Haake]

Hi,
while evaluating our implemented syscall stubs i figured out that printf does not work as expected for our small embedded arm project. (with arm-elf toolchain)
I've implemented sbrk and it seems to work. Even if I use iprintf or siprintf, which should not use malloc from what I figured out I do not end up in write syscall from where I want to put the formatted string to serial out. Shouldn't a printf always end up in the write syscall? What can go wrong within the newlib to not end up in "write"?
I would appreciate any help.
Christian

PS: this is how I configure the newlib: ./configure --target=$targ --prefix=$libc --disable-newlib-supplied-syscalls (where $targ is arm-elf)