Re: Google Embedded Controller blob - how does that get to the EC?

[James Feeney]

> If you do need to update the EC firmware, just flash it manually. Don't bother with the automatic update. It doesn't make sense for you to build it into the firmware.

Thanks.  That makes more sense.  Though still, I don't know where or when this "automatic update" happens.  Maybe it happens when ChromeOS itself starts?  If that is the case, then the EC update would *never* happen automatically if ChromeOS is replaced with something else.  On the other hand, if the EC binary itself is somehow searching the CPU ROM for an EC ROM image, then it might get confused if there is no EC ROM image to find.  Maybe Matt knows how this works?  Matt?

I also see that the Google flashrom fork seems to know how to do this update manually, if a filesystem exists, where http://goo.gl/i5sMq , "Flashrom @ Chromium.org", has:

Similarly, to write the x86 and EC firmware ROMs (assume write-protection disabled):
 flashrom -p internal:bus=spi -w bios.bin    # write x86 firmware
 flashrom -p internal:bus=lpc -w ec.bin      # write EC firmware

As far as I know, linux does not know how to directly mount a ROM coreboot filesystem.

Google Embedded Controller blob - how does that get to the EC?

[Matt DeVillier]

it seems our messages crossed since my reply addressed all this I believe :)

On Sun, Dec 17, 2023 at 1:50 PM James Feeney  wrote:
> > If you do need to update the EC firmware, just flash it manually. Don't
>
> bother with the automatic update. It doesn't make sense for you to build it
> into the firmware.
>
> Thanks.  That makes more sense.  Though still, I don't know where or when
> this "automatic update" happens.  Maybe it happens when ChromeOS itself
> starts?  If that is the case, then the EC update would *never* happen
> automatically if ChromeOS is replaced with something else.  On the other
> hand, if the EC binary itself is somehow searching the CPU ROM for an EC
> ROM image, then it might get confused if there is no EC ROM image to find.
> Maybe Matt knows how this works?  Matt?
>
> I also see that the Google flashrom fork seems to know how to do this
> update manually, if a filesystem exists, where http://goo.gl/i5sMq ,
> "Flashrom @ Chromium.org", has:
>
> Similarly, to write the x86 and EC firmware ROMs (assume write-protection
> disabled):
>  flashrom -p internal:bus=spi -w bios.bin    # write x86 firmware
>  flashrom -p internal:bus=lpc -w ec.bin      # write EC firmware
>
> As far as I know, linux does not know how to directly mount a ROM coreboot
> filesystem.