Re: .eh_frame section on alpha

[Ian Lance Taylor <ian at airs dot com>]

Simon Burge <simonb@wasabisystems.com> writes:

> http://sources.redhat.com/ml/binutils/2003-05/msg00863.html added the
> generation of a .eh_frame section to all objects that otherwise didn't
> have them.
> 
> On NetBSD, we have some tight code size constraints for our first stage
> boot loader - it needs to fit in 7.5k of space at the start of the disk.
> With binutils 2.14, our boot loader was 6880 bytes.  With binutils 2.15,
> the boot loader is 7848.  The only difference in size between the two is
> the .eh_frame section:
> 
>   3 .eh_frame     000003c4  0000000020001990  0000000020001990  00001a40  2**3
>                   CONTENTS, ALLOC, LOAD, READONLY, DATA
> 
> What exactly is this section used for?  A bit of googling seems to
> indicate it's for exception handling, which isn't a C issue.
> 
> More importantly, how can I disable the generation of this section?  It
> seems that only alpha generates an .eh_frame section unconditionally.

Hi Simon.  I haven't tested it, but there should be two ways to
disable to automatic creation of the .eh_frame section: 1) do not emit
the directives which create one--.ent, .end, .frame, etc.; 2) create
your own .eh_frame section and put nothing in it--for example, the
assembler doesn't generate its own unwind information for compiled
code, because the compiler creates a .eh_frame section anyhow.

However, I also think it would be a good idea to have an assembler
option to not create the unwind information.

Ian