On Sat, March 24, 2018 7:58 pm, Nico Huber wrote: > On 24.03.2018 13:49, awokd via flashrom wrote:
> I haven't fully followed the power rails in the schematics. Though, > what you witnessed sounds much like you also power the PCH and maybe the EC > too. The overall board layout regarding the SPI flash looks astonishing. I > wonder why it works at all ;) "Astonishing" is not very promising sounding. :) > You might already know the `laptop=force_I_want_a_brick` option for > internal flashing. This option was introduced because of severe trouble > with *less* complex situations. It looks like Wistron already placed two > masters on the SPI bus (it should only be one) and your programmer is the > third. I missed that completely. > If I understand things correctly, the flash chip is shared as much as > possible (understandable for such a cheap machine). I'm prepared to sacrifice this machine on the altar of knowledge, although I am going to miss the nice keyboard. > 1. the EC stores its > firmware in it. 2. the ME loads some of its firmware directly over SPI. 3. > the BIOS is loaded over LPC through the EC (that's the I_want_ a_brick > scenario). My vague guess is that it only works because the EC can somehow > predict when the ME is going to access the SPI flash (e.g. within some ms > after enabling certain power rails). > > I see three solutions here: > > > 1. Desolder the flash chip completely. If you just want to flash once, > solder it back afterwards. Otherwise, add some isolation circuit. > 2. Replace R6010 and R6011 with diodes. Make sure to remove all bat- > teries and AC, and power the flash chip directly during programming. > 3. Cut the VCC pin of the flash chip, solder it together again later (I've heard > people are doing that). > > My personal choice would be 2., I would never try 3. (chances are too > high that you hurt the pad below the VCC pin). Was hoping to avoid soldering (anything finer than 12 gauge makes me nervous) but sounds like no choice. I don't follow how desoldering/soldering 8 or 2 legs is safer than 1 but I'm sure there's something on Youtube explaining. Maybe it's easier than I think and I just need to practice. If I can't get it, you might see my own contribution of a special method of removing ME by judicious application of 220V AC. Thanks for taking a look! _______________________________________________ flashrom mailing list [email protected] https://mail.coreboot.org/mailman/listinfo/flashrom
