diff options
Diffstat (limited to 'roms/vbootrom/README.md')
| -rw-r--r-- | roms/vbootrom/README.md | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/roms/vbootrom/README.md b/roms/vbootrom/README.md new file mode 100644 index 000000000..808781d79 --- /dev/null +++ b/roms/vbootrom/README.md @@ -0,0 +1,44 @@ +# Virtual Boot ROM for NPCM7xx SoCs + +This is not an officially supported Google product. + +This is a super simple Boot ROM that is intended to be used as a `-bios` image +for [QEMU](http://www.qemu.org/) when emulating an NPCM7xx-based machine. + +## Building + +If you have a 32-bit ARM compiler installed as `arm-none-eabi-gcc`, simply run +`make`. + +If your ARM compiler has a different name, you'll need to override the +`CROSS_COMPILE` prefix, e.g. like this: + +``` +make CROSS_COMPILE=arm-linux-gnueabi- +``` + +If either case is successful, a `npcm7xx_bootrom.bin` file will be produced. + +## Using + +The Boot ROM image may be passed to a QEMU system emulator using the `-bios` option. For example like this: + +``` +qemu-system-arm -machine quanta-gsj -nographic \ + -bios "${IMAGES}/npcm7xx_bootrom.bin" + -drive file="${IMAGES}/image-bmc,if=mtd,bus=0,unit=0,format=raw,snapshot=on" +``` + +## Limitations + +* Secure boot is not supported. +* Only booting from offset 0 of the flash at SPI0 CS0 is implemented. +* Fallback images (if the first image doesn't boot) are not implemented. +* Exception vectors are copied to SRAM, but not remapped. +* Most OTP bits and straps are not honored. +* The reset type bits are not updated. +* OTP protection is not implemented. +* No clock initialization is performed. +* UART programming protocol is not implemented. +* Host notification through the PCI mailbox is not implemented. +* Most fields in the ROM status structure are not set. |