Re: tracepoint maintainance models

[Vara Prasad <prasadav@us.ibm.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.

>  
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>>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 ?
>
>  
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No, gcc doesn't do that today.