On Tue, Dec 05, 2017 at 04:56:37PM +0100, Maxime Ripard wrote:
Hi,
Here is a set of patches that have been sitting in some variations for quite some time now.
This is mostly to ease the eMMC (and MMC, to some extent) flashing using fastboot that in turn rely on GPT.
The Allwinner SoCs need to have the SPL located right in the middle of a traditional GPT, at 8kB.
To deal with this, we would basically have two options:
- Use the already in-tree solution to move the partition entries to another arbitrary offset in the MMC.
- Use a smaller number of partitions entries
Both are non-standards, but are dealt with nicely by the regular tools and users (at least on a Linux system). However, the first solution is quite confusing for users (that needs to be aware where the partitions will be), might be less flexible because not all tools will allow to create partitions for things between the GPT main entry and the partition entries, and might confuse tools if such a setup is available.
In our case, using the first solution, gdisk will for example refuse to create a partition for the SPL.
The second solution though seems to be well handled by all the tools, and just feels the same, except that you end up with a smaller number of partitions. In our case, that number is 56 partitions (16 sectors before the SPL, 1 sector for the protective MBR, 1 sector for the GPT header, and 4 partition entries per sector) instead of 128, which doesn't sound very impractical either.
The two first patches deal with that.
We then provide a default partitionning scheme. I'd like feedback on that one. I appreciate that having a good default in such a case, but I'd like to have a reasonably simple layout that works good enough to install a distro. I'm a bit short on background on what an EFI partition is supposed to look like, and what a good size would be. I'd really like some input on this.
Finally, we enable fastboot flashing to be able to flash a pristine system just by using FEL, fastboot oem format, and then fastboot flash for the various components.
Merged.
Maxime