Hi Desone,
On Tue, 14 Nov 2023 at 17:43, Desone Burns dburns@seegrid.com wrote:
Hello,
I have an application in which I need to boot an x86-64 machine with a legacy BIOS. I've read about the U-Boot executable, the SPL, and the TPL. I'm just having a bit of trouble figuring out which pieces are supposed to go where. Looking to Grub, I see there exists a minimal "boot.img" file, which gets installed into the MBR of the drive and subsequently bootstraps the rest of the sequence. My impression was that either the TPL or the SPL would play that same role, but even removing basically all options, the binary produced is still too large to fit in this 512 Byte area. Syslinux also works on my device, and the "mbr.bin" and "gptmbr.bin" files play the same role for that bootloader. How can I make optimizations to generate an image small enough to fit into the MBR of my device to allow BIOS to load the rest of the bootloader?
Normally U-Boot would go in the SPI flash. If you are wanting to put U-Boot on a disk, then I suspect you need some code in the MBR to load it into RAM.
Something like [1] perhaps?
For that case, I doubt you need TPL and SPL...we use those on newer x86 machines, e.g. Apollo Lake - see [2]
Regards, Simon
[1] https://thestarman.pcministry.com/asm/mbr/STDMBR.htm [2] https://docs.u-boot.org/en/latest/board/google/chromebook_coral.html?highlig...