Re: tracepoint maintainance models

From: Vara Prasad
Date: Mon Sep 18 2006 - 16:29:27 EST


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.


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