Re: tracepoint maintainance models

[Vara Prasad <prasadav at us dot ibm dot com>]

Alan Cox wrote:

> Ar Llu, 2006-09-18 am 12:10 -0700, ysgrifennodd Vara Prasad:
>  
>
> > I am not sure i quiet understand your line number part of the proposal. 
> > Does this proposal assume we have access to source code while generating 
> > dynamic probes?
> >    
>
> Its one route - or we dump it into an ELF section in the binary.
>  
Source code access is not a good solution but ELF section could work.

>  
>
> > This still doesn't solve the problem of compiler optimizing such that a 
> > variable i would like to read in my probe not being available at the 
> > probe point.
> >    
>
> Then what we really need by the sound of it is enough gcc smarts to do
> something of the form
>
> 	.section "debugbits"
> 	
> 	.asciiz 'hook_sched'
> 	.dword l1	# Address to probe
> 	.word 1		# Argument count
> 	.dword gcc_magic_whatregister("next"); [ reg num or memory ]
> 	.dword gcc_magic_whataddress("next"); [ address if exists]
>
>
> Can gcc do any of that for us today ?
>
>  
No, gcc doesn't do that today.