[U-Boot] [PATCH v1 0/2] disk: efi: allow gap before partition entries

[Rask Ingemann Lambertsen <rask@formelder.dk>]

On Fri, Feb 17, 2017 at 06:31:29PM +0100, Philipp Tomsich wrote:
> Motivated by the the SPL layout for SD/MMC devices on Allwinner SoCs
> (the SPL code needs to reside an 8K offset into the device), we add
> support for leaving a gap between the MBR (LBA#0), GPT header (LBA#1)
> and GPT partition entries (linked from field in the GPT header).
> 
> Note that this affects the creation of partition from U-Boot only and
> has no effect on reading existing partition tables.
> 
> If defined, EFI_PARTITION_ENTRIES_OFF specifies a byte-offset into
> a device and the parititon entries will be located starting at the
> next LBA folling this offset.

In principle, this isn't really EFI specific, because all partition table
formats will need to avoid the SPL area, so the configuration string
shouldn't include the word EFI. EFI just happens to be the only(?) partition
table format which is bloated enough to not easily fit into the space before
the SPL area.

Also, it seems to me that there should also be a way of specifying how much
room is available before the SPL area. So you could have
CONFIG_SPL_AREA_START and CONFIG_SPL_AREA_SIZE, which added together gives
the same value as your EFI_PARTITION_ENTRIES_OFF.

-- 
Rask Ingemann Lambertsen