about oprofile callgraph on linux-mips

about oprofile callgraph on linux-mips

[Amker.Cheng]

Hi,
    Previously I have run oprofile on linux-mips and have two
questions about it.
    It seems that oprofile does not support callgraph on linux-mips
currently, since there is no
backtrace function in oprofile kernel module for mips target.
    Is it possible or easy to support callgraph on mips target? If I
am right, it's some kind of
difficult to calculate stack frames of interrupted user space
programs, at least for O32 ABI.

Any tips would be appriciated. thanks.


-- 
Best Regards.

Re: about oprofile callgraph on linux-mips

[David Daney]

On 01/17/2011 07:01 PM, Amker.Cheng wrote:
> Hi,
>      Previously I have run oprofile on linux-mips and have two
> questions about it.
>      It seems that oprofile does not support callgraph on linux-mips
> currently, since there is no
> backtrace function in oprofile kernel module for mips target.
>      Is it possible or easy to support callgraph on mips target? If I
> am right, it's some kind of
> difficult to calculate stack frames of interrupted user space
> programs, at least for O32 ABI.
>

By default, most MIPS code doesn't use frame pointers.  This makes 
generating an accurate stack trace either very difficult or impossible.

If you compile *all* your user space code with -fno-omit-framepointer, 
you could write a fairly simple stack walker.  Otherwise you have to do 
code analysis to try to get a stack trace, and that is quite complex, 
and at in some cases impossible.

> Any tips would be appriciated. thanks.

I wrote a userspace o32 stack trace generator once and posted it to 
java-patches@gcc.gnu.org.  If you search for it you might find it.

David Daney