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Re: Use of -Werror in systemtap Module Makefiles


Frank Ch. Eigler wrote:

David Wilder <dwilder@us.ibm.com> writes:



We are using -Werror in the tap modules Makefile causing the following
error during module builds. [...]
[...]
/usr/local/share/systemtap/runtime/vsprintf.c: In function '_stp_vsnprintf':
/usr/local/share/systemtap/runtime/vsprintf.c:428: warning: frame size
of '_stp_vsnprintf' is 256 bytes
[...]



This actually looks good to know. With probes running in potentially small amounts of stack space, stack hogs need to thin down. Martin, would it be easy to improve this (by e.g. using fewer locals)?



I agree this is good to know, when we are in development. But what about the user that has no clues of the details? If he pulls a new kernel and source tree from the distro and stap stops working he will need help to fixit. Not to mention once he know how to fixit he will have to carry over the fix the next time he updates the kernel.

How about making the -Werror a stap option for developers to find areas for improvements?

Should -Werror be removed from the systemtap module build?



I suspect that the flag is on the whole worth keeping - to help ensure that the translator is generating clean code.




/usr/local/share/systemtap/runtime/stack.c: In function
'_stp_stack_sprintj':
/usr/local/share/systemtap/runtime/stack.c:338: warning: 'stack' may
be used uninitialized in this function [...]



This too might be easily worked around by tweaks to the runtime code. I'd rather see that done than to make all warnings go away quietly.



Yes we should tweak the runtime to eliminate as may warnings as we can. But don't let the user find our dirt :)

- FChE




--
David Wilder
IBM Linux Technology Center
Beaverton, Oregon, USA dwilder@us.ibm.com
(503)578-3789



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