Jerry Van Baren wrote:
Wolfgang Denk wrote:
Hello,
I'm trying to figure out what could be done to add (at least in some cases) more information to U-Boot images.
In this case, the existing CRC32 checksum is not sufficient; therequirement is to use some stronger hashes (md5 or sha1) to verify the correctness of the kernel and file system images.
A similar thing happened not so long ago when we discussed how to add the OFT blob.
Here some thoughts:
- The original 64 byte header is tabu and cannot be changed to provide
compatibility to existing versions.
- A quick & dirty hack could use a multi-file image to add - for
example - the SHA1 checksum as separate image in addition to the kernel (and eventually file system) image(s).
Add an OFT blob, and the confusion is perfect.
Seems we need a more structured approach.
I would like to use this opportunity to collect ideas and suggestions for a more generalized solution that is flexible and extensible enough to handle not only the current , but also future requirements. At least some of them ;-)
All input welcome...
Best regards,
Wolfgang Denk
Two possibilities come to mind for using (abusing) the original 64 byte header:
- If we put an ASCII-hex hash _as_ the name, we could support a 16 byte
(128 bit) hash. The name would no longer be pronounceable :-P, but it _would_ be unique. An MD5 hash is typically a 32-character hexadecimal number. [Ref: http://en.wikipedia.org/wiki/MD5]
- The name is 32 bytes. If we trimmed the maximum name length to 28
bytes, we could use the last 4 bytes as a pointer to a hash. Bleah, not much/any better than the multi-file approach.
gvb
What about an image tail?. The last 2 longs of the name could be changed by: u32 tail_magic_number; /* A magic number to detect an image with a tail */ u32 tail_offset; /* Offset to the tail from the image header */
The tail structure will add the new information for the next versions of U-Boot.