On 9/5/2021 6:41 AM, Steve McIntyre wrote:
Actually, I doubt that is literally true, although there is a big asterisk involved. AFAIK, the on disk format for ext4 is the same as ext2. If the code can read an ext2 filesystem, it can read an ext4 filesystem. The "asterisk" is that older u-boots didn't know about ext4, so when they check the version of the filesystem they see a number that they don't understand and give up. So, de-facto they won't read the filesystem, although they actually could!On Sun, Sep 05, 2021 at 09:00:52AM +0900, Hideki Yamane wrote:On Sat, 4 Sep 2021 21:43:50 +0100 Steve McIntyre <steve@einval.com> wrote:Ummm. In my experience quite a number of older armel/armhf devices booting using U-Boot may *not* be able to boot using ext4.I don't have any knowledge about U-Boot and arm devices, so here's a question. Is U-Boot different on each devices? It means, U-Boot on device A can read ext4 but on device B cannot.
FWIW, I have always used a separate "boot" partition. It can waste a small amount of disk space unless you pay close attention to how big it needs to be, but it is never written to (almost) and therefore is much less likely to be damaged by some hardware, software, or operator error. TBH, it is also because "back in the day" many bios couldn't read a large disk and the boot partition had to be on low cylinder numbers. In any case, it is a simple thing to do and has no down side AFAIK. Having this as the default behavior seems like a good idea to me😁.
Bill Campbell
That's correct. U-Boot is often forked by vendors, then built with their own special config. Depending on the age of the board (and the fork!), I've seen lots of different issues here. :-(