[U-Boot] [PATCH v3 07/10] x86: Support a chained-boot development flow

[Bin Meng]

On Wed, Mar 16, 2016 at 9:44 PM, Simon Glass <sjg at chromium.org> wrote:
> Sometimes it is useful to jump into U-Boot directly from coreboot or UEFI
> without any 16-bit init. This can help during development by allowing U-Boot
> to avoid doing all the init required by the platform.
>
> U-Boot expects its GDT to be set up correctly by its 16-bit code. If
> coreboot doesn't do this (because it hasn't run the payload setup code yet)
> then this won't happen.
>
> In this case we cannot rely on the GDT settings. U-Boot will hang or crash
> if these are wrong. Provide a development-only option to set up the GDT
> correctly. This is just a hack so you can jump to U-Boot from any stage of
> coreboot, not just at the end.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
> Changes in v3:
> - Add more detail to the commit message and code comments
>
> Changes in v2: None
>
>  arch/x86/cpu/start.S | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 80 insertions(+)
>

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>