132 lines
5.5 KiB
Markdown
132 lines
5.5 KiB
Markdown
---
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title: ThinkPad X60 Tablet Recovery guide
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x-unreviewed: true
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...
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This section documents how to recover from a bad flash that prevents
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your ThinkPad X60 Tablet from booting.
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ROM images for this machine are well-tested in Libreboot, so bricks are rare.
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The most common cause of a brick is operator error, when flashing a ROM image.
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In *most* cases, the cause will be that there is no bootblock, or an invalid
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one.
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Brick type 1: bucts not reset. {#bucts_brick}
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==============================
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You still have Lenovo BIOS, or you had libreboot running and you flashed
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another ROM; and you had bucts 1 set and the ROM wasn't dd'd.\* or if
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Lenovo BIOS was present and libreboot wasn't flashed.
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There are *2* 64KiB bootblocks possible, in the upper part of the ROM image.
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By default (bucts set to 0), the top one is used. If bucts is set to 1, the
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lower one (the one before the top one) is used. This bootblock is the first
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code that executes, during *romstage* as per coreboot hardware initialization.
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BUC is short for *Backup Control* and TS is short for *Top Swap*. This is a
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special register on Intel platforms. Lenovo BIOS sets PRx registers, preventing
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software re-flashing, but there is a bug in the protection, allowing everything
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*except* the upper 64KiB from being flashed. By default, coreboot only puts a
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bootblock in the upper region. If you flash such a ROM, while bucts is set to 1,
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the system won't boot because there's not a valid bootblock; this is common if
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you're re-flashing when coreboot is already installed, and you didn't set bucts
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back to 0.
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When you install on X60/T60 the first time, you set this bucts bit to 1, then
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you re-flash a second time and set it back to 0.
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In this case, unbricking is easy: reset BUC.TS to 0 by removing that
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yellow cmos coin (it's a battery) and putting it back after a minute or
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two:\
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\
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\*Those dd commands should be applied to all newly compiled X60 ROM
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images (the ROM images in libreboot binary archives already have this
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applied!):
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dd if=coreboot.rom of=top64k.bin bs=1 skip=$[$(stat -c %s coreboot.rom) - 0x10000] count=64k
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dd if=coreboot.rom bs=1 skip=$[$(stat -c %s coreboot.rom) - 0x20000] count=64k | hexdump
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dd if=top64k.bin of=coreboot.rom bs=1 seek=$[$(stat -c %s coreboot.rom) - 0x20000] count=64k conv=notrunc
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(doing this makes the ROM suitable for use when flashing a system that
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still has Lenovo BIOS running, using those instructions:
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<http://www.coreboot.org/Board:lenovo/x60/Installation>.
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Brick type 2: bad ROM image {#recovery}
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===========================================
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In this instance, you might have flashed a ROM without the top bootblock copied
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to the lower 64KiB section in the ROM, and you flashed the ROM for the first
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time (from Lenovo BIOS), in which case there is not a valid bootblock.
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In this scenario, you compiled a ROM that had an incorrect
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configuration, or there is an actual bug preventing your system from
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booting. Or, maybe, you set BUC.TS to 0 and shut down after first flash
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while Lenovo BIOS was running. In any case, your system is bricked and
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will not boot at all.
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"Unbricking" means flashing a known-good (working) ROM. The problem:
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you can't boot the system, making this difficult. In this situation,
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external hardware (see hardware requirements above) is needed which can
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flash the SPI chip (where libreboot resides).
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Remove those screws:\
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Remove the HDD:\
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Push keyboard forward to loosen it:\
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Lift:\
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Remove those:\
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Also remove that (marked) and unroute the antenna cables:\
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For some X60T laptops, you have to unroute those too:\
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Remove the LCD extend board screws. Also remove those screws (see blue
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marks) and remove/unroute the cables and remove the metal plate:\
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Remove that screw and then remove the board:\
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This photo shows the flash location:\
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This photo shows an SPI flasher used, with SOIC8 test clip:\
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Refer to the external flashing guide:
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[Externally rewrite 25xx NOR flash via SPI protocol](spi.md)
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NOTE: Do not use the 3.3v rail from your SPI programmer. Leave that disconnected.
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For 3.3v, plug your charger into the mainboard (but do not power on the mainboard)
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when the clip is connected. Before removing the clip, disconnect the charger.
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This will provide adequate 3.3v DC at correct current levels. The SPI flash on an
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X60 Tablet shares a common 3.3V rail with many other components on the mainboard,
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which all draw a lot of current, more than most flashers can provide.
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Example command:
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sudo ./flashrom -p linux_spi:dev=/dev/spidev0.0,spispeed=4096 -w libreboot.rom -V
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If flashrom complains about multiple flash chips detected, just pass the `-c`
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option as it suggests, and pick any of the chips it lists. `spispeed=4096` or
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lower (e.g. `spispeed=512`) is recommended on this board. The flashing becomes
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unstable, on this machine, when you use higher speeds.
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Reverse the steps to re-assemble your system, after you've flashed the chip.
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