[U-Boot] [PATCH] x86: Use microcode update from device tree for all processors

[Ivan Gorinov]

Hi Bin,

On Wed, Apr 18, 2018 at 07:05:28PM -0600, Bin Meng wrote:
> >> >
> >> > If there is no ROM image, ucode_base and ucode_size are not initialized and
> >> > the microcode update data from DTB applied by microcode_update_intel() to the
> >> > bootstrap CPU is not used by the multiprocessing code.
> >>
> >> Correct. If it's not a ROM image, which means U-Boot is probably not
> >> the 1st stage bootloader, which means updating microcode is not
> >> necessary. So is there any issue with current implementation?
> >
> > If the 1st stage bootloader is running from the on-chip SRAM, there may be
> > not enough space to include the microcode update data. In this case, U-Boot
> > is a secondary boot loader but still has to update the microcode.
> 
> Thanks for the information. Correct, if that's the case, then we
> should tune our codes to support that.
> 
> But I guess the "1st stage" bootloader is loaded by some on-chip
> BOOTROM to the internal SRAM?

Correct.

> Is the "1st stage" bootloader running from SRAM the U-Boot SPL? Or
> some proprietary implementation?

It's usually a proprietary implementation.