[PATCH v2 1/1] spl: allow loading via partition type GUID

[Tom Rini]

On Thu, Feb 16, 2023 at 06:19:11PM +0100, Heinrich Schuchardt wrote:
> 
> 
> On 2/16/23 18:01, Tom Rini wrote:
> > On Thu, Feb 16, 2023 at 04:29:56PM +0100, Heinrich Schuchardt wrote:
> > 
> > > Some boards provide main U-Boot as a dedicated partition to SPL.
> > > Currently we can define either a fixed partition number or an MBR
> > > partition type to define which partition is to be used.
> > > 
> > > Partition numbers tend to conflict with established partitioning schemes
> > > of Linux distros. MBR partitioning is more and more replaced by GPT
> > > partitioning.
> > > 
> > > Allow defining a partition type GUID identifying the partition to load
> > > main U-Boot from.
> > > 
> > > Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> > [snip]
> > > +config SYS_MMCSD_RAW_MODE_U_BOOT_GPT_PARTITION_TYPE
> > > +	string "GPT Partition Type on the MMC to load U-Boot from"
> > > +	depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_GPT_PARTITION_TYPE
> > > +	default d2f002f8-e4e7-4269-b8ac-3bb6fabeaff6
> > 
> > Is there a reason to use any other GUID value here? If not, just define,
> > or use it directly with a comment.  If there is a reason for other
> > values to be used:
> 
> Board vendors already differ in the partition GUIDs they use, e.g.
> 
> SiFive:
> SPL: 5B193300-FC78-40CD-8002-E86C45580B47
> Main U-Boot: 2E54B353-1271-4842-806F-E436D6AF6985
> 
> StarFive
> SPL: 2E54B353-1271-4842-806F-E436D6AF6985 (sic)
> 
> Microchip Icicle Board:
> SPL: 21686148-6449-6E6F-744E-656564454649
> 
> Using unique IDs per board allow to create SD card images where U-Boot for
> multiple boards is installed in parallel:
> 
> The boot ROM will select the board specific SPL via a unique ID and then SPL
> will use another unique ID to load the matching main U-Boot.
> 
> I only added a default value here to provide a formatting sample.

Thanks for elaborating.  It might be helpful to put something in a
follow-up patch about these use cases under doc/

-- 
Tom
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