From: Mark Wielaard <mark@klomp.org>
To: Sasha Da Rocha Pinheiro <darochapinhe@wisc.edu>
Cc: "elfutils-devel@sourceware.org" <elfutils-devel@sourceware.org>
Subject: Re: Read .debug_line without .debug_info
Date: Mon, 26 Mar 2018 19:12:00 -0000 [thread overview]
Message-ID: <20180326191201.GC9061@wildebeest.org> (raw)
In-Reply-To: <BY2PR06MB88661D28F002212597606E7A6AD0@BY2PR06MB886.namprd06.prod.outlook.com>
Hi Sasha,
On Mon, Mar 26, 2018 at 04:41:06PM +0000, Sasha Da Rocha Pinheiro wrote:
> is it possible to read contents of .debug_line section without the
> presence of a .debug_info section?
No, because .debug_line sections need some information from the CU
which comes from the .debug_info. In particular the directory table
starts with the compilation directory which can only be gotten from
the CU (DW_AT_comp_dir). The files in the file list (which don't have
an explicit dir associated) are all given relative to that comp dir.
A line table can only be gotten through a CU DIE (from the .debug_info).
But DWARF5 did make some changes that mean the .debug_line tables
can stand on their own (and have their own .debug_line_str section
for the dir and file names). I am about to post patches for that.
But I haven't thought about adding an interface to iterate through
the line tables without associated CUs. It would be nice if that
also worked for pre-DWARF5 line tables. But how to represent the
missing information?
> We have CUDA binaries being generated with only .debug_line, and we
> wish to use that. Is it possible to do that with libdw?
Not at the moment. Sorry.
> If not, any ideas of how to construct a minimum .debug_info in order
> to read it?
At the moment you need a minimal CU DIE with a DW_AT_stmt_list pointing
to the line table, a DW_AT_name for the primary source file and a
DW_AT_comp_dir for the compilation directory to resolve any relative
file.
Cheers,
Mark
next prev parent reply other threads:[~2018-03-26 19:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 16:41 Sasha Da Rocha Pinheiro
2018-03-26 19:12 ` Mark Wielaard [this message]
2018-03-26 19:25 ` Torsten Polle
2018-03-27 9:09 ` Mark Wielaard
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