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commit 1e07d74d562d72247af3a5567c2902a8ac1e418d
parent 51b72961868aeec5081d5f49b531229b97747183
Author: Francis Rowe <info@gluglug.org.uk>
Date:   Sat, 23 May 2015 21:24:06 +0100

docs/install/x200_external: update notes about GPIO33

Diffstat:
docs/install/x200_external.html | 61++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/docs/install/x200_external.html b/docs/install/x200_external.html @@ -22,6 +22,17 @@ can also be followed (adapted) if you brick your X200, to know how to recover. </p> + + <ul> + <li><a href="#flashchips">Flash chips</a></li> + <li><a href="#macaddress">MAC address</a></li> + <li><a href="#clip">Initial BBB configuration and installation procedure</a></li> + <li><a href="#boot">Boot it!</a></li> + <li><a href="#wifi">Wifi</a></li> + <li><a href="#wwan">wwan</a></li> + <li><a href="#memory">Memory</a></li> + <li><a href="#gpio33">X200S and X200 Tablet users: GPIO33 trick will not work.</a></li> + </ul> <p><a href="index.html">Back to main index</a></p> </div> @@ -127,8 +138,6 @@ chip on those pins? Check the list of SOIC-8 flash chips at <a href="../hcl/gm45_remove_me.html#flashchips">../hcl/gm45_remove_me.html#flashchips</a> but do note that these are only 4MiB (32Mb) chips. The only X200 SPI chips with 8MiB capacity are SOIC-16. For 8MiB capacity in this case, the X201 SOIC-8 flash chip (Macronix 25L6445E) might work. - Another possible solution: ground GPIO33 and boot up in non-descriptor mode. This might make software flashing possible, if - it's possible to circumvent any flashing protections that might exist. </p> <h2> @@ -332,7 +341,7 @@ Verifying flash... VERIFIED. <div class="section"> - <h2> + <h2 id="boot"> Boot it! </h2> <p> @@ -347,6 +356,52 @@ Verifying flash... VERIFIED. </p> </div> + + <div class="section"> + <h2 id="gpio33"> + X200S and X200 Tablet users: GPIO33 trick will not work. + </h2> + <p> + sgsit found out about a pin called GPIO33, which can be grounded to disable the flashing protections + by the descriptor and stop the ME from starting (which itself interferes with flashing attempts). + The theory was proven correct; however, it is still useless in practise. + </p> + <p> + Look just above the 7 in TP37 (that's GPIO33):<br/> + <img src="../hcl/images/x200/gpio33_location.jpg" alt="" /> + </p> + <p> + By default we would see this in lenovobios, when trying flashrom -p internal -w rom.rom: + </p> +<pre> +FREG0: Warning: Flash Descriptor region (0x00000000-0x00000fff) is read-only. +FREG2: Warning: Management Engine region (0x00001000-0x005f5fff) is locked. +</pre> + <p> + With GPIO33 grounded during boot, this disabled the flash protections as set + by descriptor, and stopped the ME from starting. The output changed to: + </p> +<pre> +The Flash Descriptor Override Strap-Pin is set. Restrictions implied by +the Master Section of the flash descriptor are NOT in effect. Please note +that <b>Protected Range (PR) restrictions still apply.</b> +</pre> + <p> + The part in bold is what got us. This was still observed: + </p> +<pre> +PR0: Warning: 0x007e0000-0x01ffffff is read-only. +PR4: Warning: 0x005f8000-0x005fffff is locked. +</pre> + + <p> + It is actually possible to disable these protections. Lenovobios does, + when updating the BIOS (proprietary one). One possible way to go about this + would be to debug the BIOS update utility from Lenovo, to find out + how it's disabling these protections. Some more research is available here: + <a href="http://www.coreboot.org/Board:lenovo/x200/internal_flashing_research">http://www.coreboot.org/Board:lenovo/x200/internal_flashing_research</a> + </p> + </div> <div class="section">