Thoughts or conclusions on coreboot and link time optimization (LTO)?

[Paul Menzel]

Dear coreboot folks,


in #coreboot on <irc.freenode.net> Stefan mentioned that link time
optimization (LTO) [1] might yield some speed improvements for coreboot
as the resulting firmware image might be smaller and therefore it takes
less time to read it from flash.

As LTO has been greatly improved in GCC 4.9.0 and is all over the news,
has somebody already experimented with LTO or created patches or tools
for testing?

Is somebody able to share conclusions already? That’d be very
interesting.


Thanks,

Paul


[1] http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
    (search for `lto`)

[Paul Menzel]

Dear coreboot folks,


Am Donnerstag, den 24.04.2014, 23:39 +0200 schrieb Paul Menzel:
> in #coreboot on <irc.freenode.net> Stefan mentioned that link time
> optimization (LTO) [1] might yield some speed improvements for coreboot
> as the resulting firmware image might be smaller and therefore it takes
> less time to read it from flash.
>
> As LTO has been greatly improved in GCC 4.9.0 and is all over the news,
> has somebody already experimented with LTO or created patches or tools
> for testing?
>
> Is somebody able to share conclusions already? That’d be very
> interesting.

looking further in April and May 2011 Scott Duplichan even sent a patch
to add an option to enable LTO [2][3], but unfortunately it was not
submitted.

Back then on AMD Persimmon with SeaBIOS as payload the boot time was
reduced from 690 ms to 640 ms. (Fun fact: UEFI firmware took 10 s on
that board.)


Thanks,

Paul
> [1] http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
>     (search for `lto`)
> [2] http://www.coreboot.org/pipermail/coreboot/2011-April/064859.html
> [3] http://www.coreboot.org/pipermail/coreboot/2011-May/064874.html