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89 lines
3.1 KiB
Plaintext
89 lines
3.1 KiB
Plaintext
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Upgrading BIOS using intel-spi
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------------------------------
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Many Intel CPUs like Baytrail and Braswell include SPI serial flash host
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controller which is used to hold BIOS and other platform specific data.
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Since contents of the SPI serial flash is crucial for machine to function,
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it is typically protected by different hardware protection mechanisms to
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avoid accidental (or on purpose) overwrite of the content.
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Not all manufacturers protect the SPI serial flash, mainly because it
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allows upgrading the BIOS image directly from an OS.
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The intel-spi driver makes it possible to read and write the SPI serial
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flash, if certain protection bits are not set and locked. If it finds
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any of them set, the whole MTD device is made read-only to prevent
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partial overwrites. By default the driver exposes SPI serial flash
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contents as read-only but it can be changed from kernel command line,
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passing "intel-spi.writeable=1".
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Please keep in mind that overwriting the BIOS image on SPI serial flash
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might render the machine unbootable and requires special equipment like
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Dediprog to revive. You have been warned!
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Below are the steps how to upgrade MinnowBoard MAX BIOS directly from
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Linux.
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1) Download and extract the latest Minnowboard MAX BIOS SPI image
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[1]. At the time writing this the latest image is v92.
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2) Install mtd-utils package [2]. We need this in order to erase the SPI
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serial flash. Distros like Debian and Fedora have this prepackaged with
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name "mtd-utils".
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3) Add "intel-spi.writeable=1" to the kernel command line and reboot
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the board (you can also reload the driver passing "writeable=1" as
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module parameter to modprobe).
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4) Once the board is up and running again, find the right MTD partition
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(it is named as "BIOS"):
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# cat /proc/mtd
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dev: size erasesize name
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mtd0: 00800000 00001000 "BIOS"
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So here it will be /dev/mtd0 but it may vary.
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5) Make backup of the existing image first:
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# dd if=/dev/mtd0ro of=bios.bak
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16384+0 records in
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16384+0 records out
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8388608 bytes (8.4 MB) copied, 10.0269 s, 837 kB/s
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6) Verify the backup
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# sha1sum /dev/mtd0ro bios.bak
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fdbb011920572ca6c991377c4b418a0502668b73 /dev/mtd0ro
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fdbb011920572ca6c991377c4b418a0502668b73 bios.bak
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The SHA1 sums must match. Otherwise do not continue any further!
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7) Erase the SPI serial flash. After this step, do not reboot the
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board! Otherwise it will not start anymore.
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# flash_erase /dev/mtd0 0 0
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Erasing 4 Kibyte @ 7ff000 -- 100 % complete
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8) Once completed without errors you can write the new BIOS image:
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# dd if=MNW2MAX1.X64.0092.R01.1605221712.bin of=/dev/mtd0
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9) Verify that the new content of the SPI serial flash matches the new
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BIOS image:
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# sha1sum /dev/mtd0ro MNW2MAX1.X64.0092.R01.1605221712.bin
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9b4df9e4be2057fceec3a5529ec3d950836c87a2 /dev/mtd0ro
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9b4df9e4be2057fceec3a5529ec3d950836c87a2 MNW2MAX1.X64.0092.R01.1605221712.bin
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The SHA1 sums should match.
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10) Now you can reboot your board and observe the new BIOS starting up
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properly.
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References
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----------
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[1] https://firmware.intel.com/sites/default/files/MinnowBoard.MAX_.X64.92.R01.zip
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[2] http://www.linux-mtd.infradead.org/
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