[Bug runtime/2497] STP_STRING_SIZE set by stap is too small

[Frank Ch. Eigler]

Hi -

hunt wrote:

> [...]
> bin_write("%1b%4b%1b%ld%4b%4b", cmd->device->sdev_state, [...])
> print_backtrace()

It's not at all your fault, but these backtrace-related examples make
binary tracing look almost silly, in terms of performance and
complexity.

It would not be a big improvement, but the following would enable
something you suggested long ago: support a printf formatting code for
backtraces.  From script, one would pass the strings created by
backtrace().  The runtime printf could expand it to print_backtrace()
internally, or perhaps even, pass a code to user-space to do it there
later.

- FChE