[U-Boot] [PATCH v2 2/2] RISCV: image: Parse Image.gz support in booti.

[Marek Vasut <marek.vasut@gmail.com>]

On 4/30/19 3:27 AM, Atish Patra wrote:

[...]

>>> 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.

-- 
Best regards,
Marek Vasut