Re: Why do some net drivers require __OPTIMIZE__?

[Daniel Jacobowitz <dan@debian.org>]

On Tue, Jan 07, 2003 at 02:33:07PM +0000, Alex Bennee wrote:
> On Mon, 2003-01-06 at 15:36, Alan Cox wrote:
> > > Does anybody know the history behind those lines? Do they serve any
> > > purpose now or in the past? Should I be nervous about compiling the
> > > kernel at a *lower* than normal optimization level? After all
> > > optimizations are generally processor specific and shouldn't affect the
> > > meaning of the C.
> > 
> > Some of our inline and asm blocks assume things like optimisation. Killing
> > that check and adding -finline-functions ought to be enough to get what
> > you expect.
> 
> It appears to go deeper than a few network drivers. Droping to -O0
> breaks a host of other sections (ipc, sockets etc.) for less than
> obvious reasons. The only source files that seem to depend on the
> __OPTIMIZE__ define are a few of the other drivers and the byteswap
> macros.
> 
> I'll investigate the gcc pages to see if there is anyway to allow
> optimisation without the out-of-order stuff that makes tracing the start
> up so hard. *sigh*

Try -O1; it's much better for debugging in general.

> I assume I can't drop the -fomit-frame-pointer for the same reason
> (inline and asm blocks assuming register assigment?).

Shouldn't matter.

> On a related note should enabling -g on the kernel CFLAGS be ok? For
> some reason vmlinux kernels compiled with -g (even after being stripped)
> seem to break the bootmem allocator on my setup. I'm trying to track
> down if this is due to some linker weirdness due to the symbol table
> being bigger than physical memory even though its not actually being
> loaded into the system.

It should be OK; it sounds like a problem with the loader you're using,
at a guess.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer