On Thu, 20 Apr 2017, Mehmet Kayaalp wrote: > Include a random filled binary in vmlinux at the space reserved with > CONFIG_SYSTEM_EXTRA_CERTIFICATE. This results in an uncompressed reserved
Random data is not always going to be completely incompressible. And just how much it could be compressed also depends on the compression engine. Failures here would be quite annoying, even if they would be rare (not just due to the randomness factor, but also depending on just how overprovisioned the space reserved for the extra certificate was when compared with the real certificate size). Maybe it would be safer if you test it for incompressability once you generated the random data (using the same compression engine that the image will use)? If it fails, add some overprovisioning and retry... Alternatively, you could ship a static file with random data that has been tested to be uncompressible "enough" for every currently supported compression engine, maybe with a bit of a safety margin just in case a future compression engine does somewhat better... -- Henrique Holschuh
