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.przyw...@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. -- Tom
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