On Mon, Jan 14, 2013 at 10:57:08AM -0800, Yinghai Lu wrote:
> please check if following is enough?
>
> + /*
> + * kernel have sentinel to set as 0xff in setup link scripts,
> + * so if bootloader just copy whole page from kernel image to
> + * get setup_header instead of clearing boot_param buffer and
> + * copying setup_header only, will leave sentinel as 0xff.
> + * With that, we can tell some fields in boot_param have
> + * invalid values, and we need to zero them in kernel.
> + */
> + __u8 sentinel; /* 0x1ef */
"The sentinel variable is set by the linker script to 0xff. If a
bootloader doesn't know about this variable and just copies the
setup_header portion and doesn't clear the boot_params buffer as it is
supposed to, it will leave the sentinel to its initial value of 0xff.
This tells the kernel that some fields in boot_params have invalid
values and we have to zero them out in the kernel."
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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