On 02/19/2014 12:10 PM, Tom Rini wrote: ...
A generic Linux distro wouldn't be installing a kernel to NAND, but would rather put it into the /boot filesystem. NAND boot is something that'd be best supported by the custom hook we discussed above.
Wait, why would a generic Linux distro be installing to eMMC but not to NAND ? Not that this series needs to be the final point in the discussion and all.
I should point out that I was talking about raw NAND MTD partitions rather than a NAND device with a regular partition table and normal filesystems within it.
If the NAND is exposed as a regular block device with a regular filesystem, then it'd look just like any other block device to a generic distro installer, and hence it could put /boot there, and this patch (or future enhancement) could certainly usefully contain a generic bootcmd_nand that used it.
However, if the NAND has hard-coded MTD partitions, and/or the partitions have no filesystem but rather contain e.g. a raw zImage/uImage, then that would require board-/SoC-specific support in the distro kernel and installer, and hence we wouldn't be talking about a *generic* installer/distro, and *generic* installers/distros are what this patch series is all about.
The commit description for this commit should have set the scene that this series is all about providing a way for a generic Linux distro to create a generic installable media set that boots the same way across n different boards with U-Boot, and similarly also to set up the installed distro filesystem in a single generic way that can boot on any board it gets installed to. It's all about avoiding board-specific boot options such as NAND, and hence may well not be applicable to boards that primarily/only boot from NAND; they would still need custom distro install media and hooks to set up the installed filesystem.
Why is NAND special but SATA not, other than desktops often have SATA exposed but not NAND? Even more so when you consider that from the Linux side of things, dealing with NAND is dealing with NAND and it's not board specific.