On 10/11/2020 12:38, Tom Rini wrote:
Hi Tom,
On Sun, Nov 08, 2020 at 03:48:23PM +0000, André Przywara wrote:
On 08/11/2020 14:59, Peter Robinson wrote:
Hi,
On Sun, Nov 8, 2020 at 1:14 PM Andre Przywara andre.przywara@arm.com wrote:
The eMMC standard describes the concept of boot partitions, consisting of two storage areas separate from the main user data partition. The Allwinner BootROM supports loading SPL/Boot0 from such a boot partition, if that is configured in the eMMC device [1].
To load U-Boot proper along with the SPL from there, currently this requires to enable CONFIG_SUPPORT_EMMC_BOOT, and this means that this build won't boot from the normal eMMC user partition anymore. Also the raw MMC sector offset needs to be adjusted manually, preventing a boot from an SD card.
This series introduces automatic detection of eMMC boot partition boot. Patch 3/5 automates the raw MMC sector offset decision, allowing such a build to also boot from an SD card. Unfortunately the BootROM does not mark an eMMC boot partition boot differently from the normal eMMC user data partition boot, so patch 4/5 introduces a function that repeats the BootROM algorithm, so that the SPL comes to the same conclusion as the BootROM. This allows to build one single image that boots from everywhere: eMMC user data, eMMC boot, SD card, SPI flash. Patch 1/5 contains a bugfix that's needed in a later patch, patch 2/5 extends the generic spl_mmc_boot_mode() interface to make 4/5 feasible.
Without enabling CONFIG_SUPPORT_EMMC_BOOT, the AArch64 SPL grows by 92 bytes, ARMv7 grows by 36 bytes. With enabling the feature, the size goes up by 444 bytes (AArch64) and 260 bytes (ARMv7). Even for AArch64 this is still 4.5 KB below the SPL limit, so patch 5/5 enables this new mechanism for some boards I could test this on.
Please have a look and test this if you have a board with eMMC. I put installation instructions into the linux-sunxi Wiki: http://linux-sunxi.org/Bootable_eMMC
It would probably be good to put that link in the local Allwinner docs so it's easier for people to find.
Yeah, actually as you mention it: There does not seem to be some generic README.sunxi file where this would belong to.
Jagan: would it make sense to create one, and describe how to get U-Boot into the devices (SD card, eMMC, SPI flash, FEL)? That could move some parts of README.sunxi64 out of there, since they apply to all Allwinner devices.
If people agree that this is the right thing to do, I would be happy to send a patch.
Well, rST file in doc/boards/ and all of that, but, yes please.
Ah, thanks for the pointer, looks good. Do we accept symlinks in the tree? There are quite some references to board/sunxi/README.sunxi64 out there. Or shall I keep a stub instead?
Cheers, Andre