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25 lines
1.3 KiB
Plaintext
25 lines
1.3 KiB
Plaintext
8 years ago
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Much of this is educated guesswork from the observed steps, but it might
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provide a starting point for further investigation. Some of it could also
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be just plain wrong.
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My current undetstanding on how the EC flash process (as opposed to
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the BIOS one) works are as follows:
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1) dosflash loads firmware and does some validations
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2) dosflash writes firmware to a specific location in the BIOS flash
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(possibly just by handing the firmware blob to a BIOS call)
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3) dosflash reboots the machine
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4) during the BIOS Power-On-Self-Test, the BIOS notices that there
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is a EC firmware in that special area and starts the flash process
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5) The BIOS may or may not do some verification on the firmware before
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allowing it to be sent to the EC
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6) The BIOS tells the EC firmware to go into firmware update mode
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7) The old EC firmware receives the new firmware data, performing
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decryption on some of it as it goes and flashing it into the flash
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memory onboard the EC chip.
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8) When the old EC firmware has finished receiving the new firmware,
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it sends itself a reset signal and reboots into the new EC firmware.
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9) The BIOS gets confirmation from the EC that it is back up and running
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and allows the boot sequence to continue.
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