Re: tracepoint maintainance models

From: Alan Cox
Date: Mon Sep 18 2006 - 15:27:09 EST


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.

> 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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