On Tue, Jul 12, 2016 at 08:28:12PM +0200, Ladislav Michl wrote:
From: Thomas Gleixner tglx@linutronix.de
Booting a payload out of NAND FLASH from the SPL is a crux today, as it requires hard partioned FLASH. Not a brilliant idea with the reliability of todays NAND FLASH chips.
The upstream UBI + UBI fastmap implementation which is about to brought to u-boot is too heavy weight for SPLs as it provides way more functionality than needed for a SPL and does not even fit into the restricted SPL areas which are loaded from the SoC boot ROM.
So this provides a fast and lightweight implementation of UBI scanning and UBI fastmap attach. The scan and logical to physical block mapping code is developed from scratch, while the fastmap implementation is lifted from the linux kernel source and stripped down to fit the SPL needs.
The text foot print on the board which I used for development is:
6854 0 0 6854 1abd drivers/mtd/ubispl/built-in.o
Attaching a NAND chip with 4096 physical eraseblocks (4 blocks are reserved for the SPL) takes:
In full scan mode: 1172ms In fastmap mode: 95ms
The code requires quite some storage. The largest and unknown part of it is the number of fastmap blocks to read. Therefor the data structure is not put into the BSS. The code requires a pointer to free memory handed in which is initialized by the UBI attach code itself.
See doc/README.ubispl for further information on how to use it.
This shares the ubi-media.h and crc32 implementation of drivers/mtd/ubi There is no way to share the fastmap code, as UBISPL only utilizes the slightly modified functions ubi_attach_fastmap() and ubi_scan_fastmap() from the original kernel ubi fastmap implementation.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Ladislav Michl ladis@linux-mips.org Acked-by: Heiko Schocher hs@denx.de Reviewed-by: Tom Rini trini@konsulko.com
Applied to u-boot/master, thanks!