[coreboot] coreboot+seabios timings

Kevin O'Connor kevin at koconnor.net
Mon Oct 18 03:43:42 CEST 2010

On Sun, Oct 17, 2010 at 08:23:57PM -0500, Scott Duplichan wrote:
> ]> For coreboot+seabios, I get a power on to DOS boot time of around 2.7
> ]> seconds. This is with USB enabled and a 5400 rpm sata drive. While 2.7
> ]> seconds is good, there is probably room for improvement. I would like
> ]> to see a bigger coreboot advantage over UEFI. All of these numbers are
> ]> for AMD hardware with family 10h processors.
> ]
> ]Thanks.  Can you post the debug output using SeaBIOS'
> ]tools/readserial.py program?  I'd be curious to see where the time is
> ]spent.
> ]
> ]Also, try the SeaBIOS options CONFIG_THREAD_OPTIONROMS and
> ]CONFIG_ATA_DMA.  (The ATA DMA can be a little finicky though - fixing
> ]it is on my todo list.)
> I am not sure how to get that script to run from windows. I get:
> $ python ../seabios-for-coreboot/tools/readserial.py com1 115200
> Traceback (most recent call last):
>   File "../seabios-for-coreboot/tools/readserial.py", line 129, in <module>
>     main()
>   File "../seabios-for-coreboot/tools/readserial.py", line 114, in main
>     import serial
> ImportError: No module named serial

Thanks for the report.  You need the pyserial package - see:

I've updated the script to make this more descriptive.

> But it hardly matters. I think coreboot is taking most of the time. For
> example, I noticed a hesitation at:
>      "copying VGA ROM Image from %p to 0x%x, 0x%x bytes\n"

It's best to let SeaBIOS run the rom - try setting CONFIG_VGA_ROM_RUN
and CONFIG_PCI_ROM_RUN to off in coreboot.  Also, set

> With these two changes, boot time is reduced by 650 ms. Now the boot
> time is around 2.050 seconds. That is from power switch off (standby
> power on) to DOS prompt.
> By the way, I tried your other suggestions and did not see much
> of a difference. I do need to get an SSD drive because the
> randomness in the rotating drive makes precise measurements
> difficult. The DMA hardly matters for DOS where only a few KB
> are read from disk. But it could be very important for OS booting,
> where as much as hundreds of MB are read from disk using BIOS calls.

Yeah - I found the SSD to be a big win on boot times - simply because
it eliminated the spin-up delay.  I also tried USB drives and a
compact flash card with an ATA/SATA adapter, but all three exhibited
"spin-up" delays.


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