[coreboot] use gcc 4.6.0 link time optimization to reduce coreboot execution time

[Scott Duplichan]

Kevin O'Connor wrote:

] That's a great boot time!  Do you have a breakdown of where the 640ms
] is spent?
]
] -Kevin

Hello Kevin,

I tried adding some serial logging to get an idea about where
the time is spent. The logging adds 8 ms to the boot time:

Time in ms
0      cold reset
366    memory initialization complete
469    seabios: maininit(void)
483    seabios: vga_setup() called
604    seabios: vga_setup() returned
621    seabios: startBoot(void)
648    dos autoexec utility logs pmtimer value

It looks like the lengthy operations are memory init and VBIOS
execution, which is consistent with past experience.

UEFI BIOS on this same hardware platform is taking more than 
10 seconds.

Here seabios kconfig options I changed:

Build for coreboot                           y
Hardware init during option ROM execution    y
Bootmenu                                     n
ATA controllers                              n
AHCI controllers                             y
Floppy controller                            n
PS/2 port                                    n
USB UHCI controllers                         n
Parallel port                                n
PCIBIOS interface                            n
APM interface                                n
PnP BIOS interface                           n
S3 resume                                    n
SMBIOS                                       n
Serial port debugging                        y
Show screen writes on debug ports            n

Thanks,
Scott