[Libreboot] R400: Using GPIO33 to enable reflash

[Joerg Albert]

Hi,

I'm preparing to flash libreboot onto a Thinkpad R400 for the first time.

I'd prefer to have it write protected by disabling writes from the host in
the descriptors as described here:

https://libreboot.org/docs/hcl/gm45_remove_me.html#ich9gen

I wonder if the GPIO33 trick:

https://libreboot.org/docs/install/x200_external.html#gpio33)

would allow me to reflash libreboot without any external equipment (besides
shorting two pads under the WWAN slot [R653] at boot time)?

AFAIK the protected range restrictions mentioned in the link above are
implemented in the Lenovo BIOS. Does libreboot impose them as well based on
the bits in the flash descriptor table?

Regards,
Joerg