Fails to build sys/i386/boot2 with gcc 4.9

[Garrett Cooper]

> On Mar 29, 2015, at 15:56, Warner Losh <imp at bsdimp.com> wrote:
> 
>> On Mar 29, 2015, at 2:29 PM, Craig Rodrigues <rodrigc at FreeBSD.org> wrote:
>> 
>> On Sun, Mar 29, 2015 at 11:04 AM, Warner Losh <imp at bsdimp.com> wrote:
>> 
>> If we built a UFS1-only boot2, that would fit in the 7.5k we have left
>> to play with. We could then build a UFS2-only boot2 that would easily
>> fit in the like 32k limit that UFS2 has.
>> 
>> The only reason we went to supporting both was to have something
>> universal. Since it requires a reformat to go from UFS1 -> UFS2 we
>> wanted the transition to be as smooth as possible so you didn’t have
>> to add boot blocks into the mix.
>> 
>> Now the only people that use UFS1 are people with really old systems
>> that are never going to upgrade, or people building new systems with
>> UFS1 because they are space constrained (for whatever reasons that
>> we’re not going to debate here: they are still real).
>> 
>> In the past 5 years, I have worked on some embedded systems where UFS1 was chosen because of very low memory and disk space requirements.
>> So those systems are real and out there.
>> 
>> Just out of curiousity, what is it about newer compilers that cause
>> the size of boot2 to increase so much?
>> 
>> Could we do some silly things like removing/reducing the use of printf()
>> to save some more bytes, in order to buy us more time, before having
>> to rewrite everything? :)
> 
> Removing printf isn’t going to save us. It usually compiles to 80-120 bytes.
> 
> I think the only sane way forward is boot2.ufs1 an boot2.ufs2 plus maybe
> some safety belts in the boot block splatter programs to prevent
> brickification.

Since the proposal to split up the code by filesystems is on the table, would it make sense to do something similar for zfs?
Thanks!