Add support for the 32 bit boot protocol to the x86 zboot command.

On Tue, Nov 29, 2011 at 7:48 PM, Graeme Russ <[email protected] <mailto:[email protected]>> wrote:

Hi Gabe,

On Wed, Nov 30, 2011 at 2:11 PM, Gabe Black <[email protected] <mailto:[email protected]>> wrote:
> These two patches add support for the 32 bit Linux boot protocol to the > zboot command.

Going by our previous offline correspondence, I assume this approach still uses the bzImage's decompression stub?

Also, as I discussion offline previously, I'm going through the boot_params with a fine-tooth comb to get a complete picture of what the Linux kernel actually requires to be filled out in the boot_params structure - I expect this will result in a 'built_boot_params()' function which is called by zboot and bootm - possibly with some weak stubs to helper functions

Regards,

Graeme

Yes, this supports the 32 bit protocol which includes the decompression stub. I don't think a build_boot_params function which actually builds the bootstub would work for a number of reasons. First, that's not how the boot protocol works. The kernel provides information there that u-boot needs to read, and u-boot shouldn't just make it up. An example of this is what boot protocol is expected. Second, you might find all the things a particular version of the kernel wants right now, but that could easy change at any time and break booting. Third, the boot_params structure isn't compressed (because otherwise the bootloader couldn't fill it out) and building our own wouldn't serve any purpose.

If you mean consolidating the existing boot_params code so that both zboot and bootm can use it, that seems reasonable. I'd point out, though, that filling out the table takes a trivial amount of time, so trying to cut corners and not fill it out completely would not only be dangerous, it would very likely not be worth the effort.