| |
| This describes how to change the HWID string that's displayed using the |
| new-style BIOS bitmaps. For a more detailed explanation of what's going on, |
| refer to the README file. |
| |
| The HWID is encoded in the GBB in two ways: An ASCII string that userspace |
| can read from /sys/devices/platform/chromeos_acpi/HWID, and as a rendered |
| bitmap that shows up on the BIOS screens. |
| |
| |
| Here's how to generate a new bitmap blob with a modified HWID |
| |
| 1. OUTSIDE the chroot, cd to |
| src/platform/vboot_reference/scripts/newbitmaps/strings |
| |
| 2. Edit the file 'hwid.txt' to contain your new string. |
| |
| 3. Run "./text_to_bmp hwid.txt" to create "hwid.bmp" which contains ONLY the |
| picture of the HWID string. |
| |
| 4. Copy the hwid.bmp image to the directory where the rest of the bitmap |
| blob comes from (which might not be public yet). If you don't know where |
| that is, just use the example directory: |
| |
| src/platform/vboot_reference/scripts/newbitmaps/images/1280x800 |
| |
| 5. cd to the bitmap source directory, INSIDE the chroot. |
| |
| 6. Edit the .yaml file that describes the bitmap blob (if you're in the |
| 1280x800 directory, it's called "unknown.yaml"). Change the line that |
| starts with "hwid:" to refer to your new hwid.bmp file (or replace the |
| existing hwid bitmap file with your new one). |
| |
| 7. Run "bmpblk_utility -c unknown.yaml new_bitmaps.bin", to create the new |
| bitmap blob. |
| |
| 8. Install the new_bitmaps.bin on your device (see below). |
| |
| |
| |
| |
| The gbb_utility is used to replace both the ASCII string and the bitmap blob |
| in a BIOS image. The typical proces is to do this as root on the target |
| system. This will only work if THE BIOS write-protect is disabled. |
| |
| |
| A. Read the existing BIOS from ROM (so you don't lose the VPD): |
| |
| cd /mnt/stateful_partition |
| flashrom -r bios.bin |
| |
| B. Modify the GBB in the BIOS image to contain the new bits: |
| |
| gbb_utility -s 'NEW HWID STRING 1234' -b new_bitmaps.bin bios.bin |
| |
| C. Write the modified BIOS back to ROM: |
| |
| flashrom -w bios.bin |