On Mon, Oct 12, 2015 at 03:43:01PM +0200, Maxime Ripard wrote: > Hi, > > I'm currently writing the support in U-Boot for NAND-backed devices > using fastboot [1], and that work derived a bit to supporting the > sparse images. > > For "regular" images that are being stored, we expect a pair of > download and flash commands. Simple. > > Things start to get a bit more complex with sparse images that have > been split because of a max-download-size lower than the actual image > size. > > Here, from what I could gather from various random blog posts, the > fastboot client implementation and dumping a few USB sessions, the > client simply creates several download / flash pairs, always on the > same partition, without any way to distinct that from several > subsequent writes issued by the user. > > So, I'm guessing that the expectation is that the bootloader > implementation should store the last offset it wrote to, and simple > resume from there if the partition names in the flash commands are the > same, which would prevent two subsequent write on the same partition > by any client. Am I right? > > A related question is when should we erase the NAND partition? Only > when doing fastboot erase, or also when doing fastboot write (which, > combined with the issue raised above, would also mean that we don't > want to do an erase on the whole partition everytime there's a flash > command on it).
I think for this last question, some experimentation with the existing tools might be required. As there's no required explicit erase for MMC, I think it might make sense to say you erase nand up front and then write as anything else starts getting really tricky and we're just second-guessing the user. -- Tom
signature.asc
Description: Digital signature
_______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
