On 4/30/19 3:27 AM, Atish Patra wrote:
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Yes. FIT image parsing can be done in that way. However, the idea was here to load Image.gz directly. Image.gz is default compressed Linux kernel image format in RISC-V.
Sigh, and the image header is compressed as well, so there's no way to identify the image format, right ? And there's no decompressor, so the dcompressing has to be done by bootloader, which would need some sort of very smart way of figuring out which exact compression method is used ?
Yes. Image.gz is always gunzip. So checking first two bytes is enough to confirm that it is a gz file.
What happens once people start feeding it more exotic compression methods, like LZ4 or LZO or LZMA for example ?
The tricky part is length of the compressed file. I took another look at the gunzip implementation in U-Boot. It looks like to me that compressed header length just to parse the header correctly. It doesn't actually use the "length" to decompress. In fact, it updates the length with uncompressed bytes after the decompression.
That's possible.