On Thu, Dec 1, 2011 at 7:47 AM, Graeme Russ graeme.russ@gmail.com wrote:
Hi Gabe,
On 30/11/11 17:25, Gabe Black wrote:
On Tue, Nov 29, 2011 at 7:48 PM, Graeme Russ <graeme.russ@gmail.com mailto:graeme.russ@gmail.com> wrote:
Hi Gabe, On Wed, Nov 30, 2011 at 2:11 PM, Gabe Black <gabeblack@chromium.org <mailto:gabeblack@chromium.org>> wrote: > These two patches add support for the 32 bit Linux boot protocolto the
> zboot command. Going by our previous offline correspondence, I assume this approachstill
uses the bzImage's decompression stub? Also, as I discussion offline previously, I'm going through theboot_params
with a fine-tooth comb to get a complete picture of what the Linuxkernel
actually requires to be filled out in the boot_params structure - Iexpect
this will result in a 'built_boot_params()' function which is calledby
zboot and bootm - possibly with some weak stubs to helper functions Regards, GraemeYes, 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.
I've been playing around tonight and have managed to embed a gzip'd vmlinux and raw header (stripped from the associated bzImage) into my U-Boot image but I end up getting the same results - No RAM :(
So proof of concept is good
Regards
Graeme
You have to make sure you're using the 32 bit protocol. The 16 bit protocol should still work and is the default, but then the kernel tries to use other means to figure out what memory looks like. To use the 32 bit protocol, you need to define CONFIG_ZBOOT_32.
Gabe