| ============================== |
| Upgrading BIOS using intel-spi |
| ============================== |
| |
| Many Intel CPUs like Baytrail and Braswell include SPI serial flash host |
| controller which is used to hold BIOS and other platform specific data. |
| Since contents of the SPI serial flash is crucial for machine to function, |
| it is typically protected by different hardware protection mechanisms to |
| avoid accidental (or on purpose) overwrite of the content. |
| |
| Not all manufacturers protect the SPI serial flash, mainly because it |
| allows upgrading the BIOS image directly from an OS. |
| |
| The intel-spi driver makes it possible to read and write the SPI serial |
| flash, if certain protection bits are not set and locked. If it finds |
| any of them set, the whole MTD device is made read-only to prevent |
| partial overwrites. By default the driver exposes SPI serial flash |
| contents as read-only but it can be changed from kernel command line, |
| passing "intel-spi.writeable=1". |
| |
| Please keep in mind that overwriting the BIOS image on SPI serial flash |
| might render the machine unbootable and requires special equipment like |
| Dediprog to revive. You have been warned! |
| |
| Below are the steps how to upgrade MinnowBoard MAX BIOS directly from |
| Linux. |
| |
| 1) Download and extract the latest Minnowboard MAX BIOS SPI image |
| [1]. At the time writing this the latest image is v92. |
| |
| 2) Install mtd-utils package [2]. We need this in order to erase the SPI |
| serial flash. Distros like Debian and Fedora have this prepackaged with |
| name "mtd-utils". |
| |
| 3) Add "intel-spi.writeable=1" to the kernel command line and reboot |
| the board (you can also reload the driver passing "writeable=1" as |
| module parameter to modprobe). |
| |
| 4) Once the board is up and running again, find the right MTD partition |
| (it is named as "BIOS"):: |
| |
| # cat /proc/mtd |
| dev: size erasesize name |
| mtd0: 00800000 00001000 "BIOS" |
| |
| So here it will be /dev/mtd0 but it may vary. |
| |
| 5) Make backup of the existing image first:: |
| |
| # dd if=/dev/mtd0ro of=bios.bak |
| 16384+0 records in |
| 16384+0 records out |
| 8388608 bytes (8.4 MB) copied, 10.0269 s, 837 kB/s |
| |
| 6) Verify the backup: |
| |
| # sha1sum /dev/mtd0ro bios.bak |
| fdbb011920572ca6c991377c4b418a0502668b73 /dev/mtd0ro |
| fdbb011920572ca6c991377c4b418a0502668b73 bios.bak |
| |
| The SHA1 sums must match. Otherwise do not continue any further! |
| |
| 7) Erase the SPI serial flash. After this step, do not reboot the |
| board! Otherwise it will not start anymore:: |
| |
| # flash_erase /dev/mtd0 0 0 |
| Erasing 4 Kibyte @ 7ff000 -- 100 % complete |
| |
| 8) Once completed without errors you can write the new BIOS image: |
| |
| # dd if=MNW2MAX1.X64.0092.R01.1605221712.bin of=/dev/mtd0 |
| |
| 9) Verify that the new content of the SPI serial flash matches the new |
| BIOS image:: |
| |
| # sha1sum /dev/mtd0ro MNW2MAX1.X64.0092.R01.1605221712.bin |
| 9b4df9e4be2057fceec3a5529ec3d950836c87a2 /dev/mtd0ro |
| 9b4df9e4be2057fceec3a5529ec3d950836c87a2 MNW2MAX1.X64.0092.R01.1605221712.bin |
| |
| The SHA1 sums should match. |
| |
| 10) Now you can reboot your board and observe the new BIOS starting up |
| properly. |
| |
| References |
| ---------- |
| |
| [1] https://firmware.intel.com/sites/default/files/MinnowBoard%2EMAX_%2EX64%2E92%2ER01%2Ezip |
| |
| [2] http://www.linux-mtd.infradead.org/ |
