That's pretty interesting. I had no idea that would work.
I wonder if erasing it all erases that little boot of the ME you need to get the hardware going, whereas the 4KB erase lets the little bootstrap run but disables the ME otherwise. If so, that's great news.
ron
On Mon, Sep 12, 2016 at 8:43 AM Trammell Hudson hudson@trmm.net wrote:
I'm experimenting with what happens if I remove the ME firmware from from the lower SPI flash chip on my Thinkpad x230. If I just erase the first 4KB of its region (0x3000, starts with "$FPT"), coreboot boots up fine and reports that "WARNING: ME has bad firmware". My Linux payload initializes without any complaints.
The boot script then kexec's into Xen and Qubes, which works, but things like S3 sleep don't seem to kick in when I close the lid ("unknown key pressed", code e058). systemctl suspend works fine and the system wakes up when I open the lid again, so this might might be a spurious issue.
If I erase the entire ME region from 0x3000 to 0x4FFFFF the system will not boot at all. The indicator on the power button will flash when I press it, but the system does not seem to respond otherwise (I do not have a port 80 debugger or hardware serial port to see where it is failing). Reflashing with the original ME firmware restores it's functionality.
-- Trammell
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