Re: Correctly using callstack-user context - Christophe Bédard via lttng-dev

From: "Christophe Bédard via lttng-dev" <lttng-dev@lists.lttng.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: lttng-dev <lttng-dev@lists.lttng.org>
Subject: Re: Correctly using callstack-user context
Date: Wed, 13 May 2020 09:42:42 -0400	[thread overview]
Message-ID: <CAAS9dobxi52FyWn=9zVDkMMpmZztc1Q1msdiErMKhkDEYCtqCA@mail.gmail.com> (raw)
In-Reply-To: <1486835767.11198.1589286441675.JavaMail.zimbra@efficios.com>

[-- Attachment #1.1: Type: text/plain, Size: 838 bytes --]

On Tue, 12 May 2020 at 08:27, Mathieu Desnoyers <
mathieu.desnoyers@efficios.com> wrote:

> How does your test program issue the system call ? Is it directly with
> syscall() (see syscall(2) man page), or
> does it call into libc ? Is your entire libc compiled with
> -fno-omit-frame-pointer ?
>

Indirectly, through libc/libstdc++. We use the default system libs (which I
assume use -O, which in turn implies -fomit-frame-pointer).

> As soon as one library in the chain to the system call is compiled without
> frame pointers, this is where the
> stack walk stops. This is usually libc.
>

I see. Thanks for the information. Not sure we want to ship a custom libc
unfortunately.

Related question: how feasible would adding the callstack-user context to
userspace events be? If it is feasible, is such a feature planned?

Christophe

[-- Attachment #1.2: Type: text/html, Size: 1677 bytes --]

[-- Attachment #2: Type: text/plain, Size: 156 bytes --]

_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev