Re: [RFC 01/22] part: call part_init() in blk_get_device_by_str() only for MMC

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Heinrich,

On Fri, Oct 01, 2021 at 08:41:52AM +0200, Heinrich Schuchardt wrote:
> 
> 
> On 10/1/21 7:01 AM, AKASHI Takahiro wrote:
> > In blk_get_device_by_str(), the comment says: "Updates the partition table
> > for the specified hw partition."
> > Since hw partition is supported only on MMC, it makes no sense to do so
> > for other devices.
> > 
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> >   disk/part.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/disk/part.c b/disk/part.c
> > index a6a8f7052bd3..b330103a5bc0 100644
> > --- a/disk/part.c
> > +++ b/disk/part.c
> > @@ -427,7 +427,8 @@ int blk_get_device_by_str(const char *ifname, const char *dev_hwpart_str,
> >   	 * Always should be done, otherwise hw partition 0 will return stale
> >   	 * data after displaying a non-zero hw partition.
> >   	 */
> > -	part_init(*dev_desc);
> > +	if ((*dev_desc)->if_type == IF_TYPE_MMC)
> > +		part_init(*dev_desc);
> 
> For an eMMC the following logical levels exist:
> 
> * device
> * hardware partition
> * software partition
> 
> Linux might show the following:
> 
> /dev/mmcblk0 - user data area
> /dev/mmcblk0boot0 - boot hardware partition 0
> /dev/mmcblk0boot1 - boot hardware partition 1
> /dev/mmcblk0rpmb - replay protected memory block
> 
> How are the different hardware partition modeled in the UEFI device path?
> Should each hardware partition be a separate udevice?
> 
> For NOR flash we also have an extra level:
> 
> => setenv mtdparts
> mtdparts=30bb0000.qspi:1m(U-Boot),512k(Env),512k(DTB),2m(User_FS),12m(Data_FS),4m(Factory_FS),34m(Ramdisk),10m(Linux)
> => mtd
> 
> device nor0 <30bb0000.qspi>, # parts = 8
>  #: name                size            offset          mask_flags
>  0: U-Boot              0x00100000      0x00000000      0
>  1: Env                 0x00080000      0x00100000      0
>  2: DTB                 0x00080000      0x00180000      0
>  3: User_FS             0x00200000      0x00200000      0
>  4: Data_FS             0x00c00000      0x00400000      0
>  5: Factory_FS          0x00400000      0x01000000      0
>  6: Ramdisk             0x02200000      0x01400000      0
>  7: Linux               0x00a00000      0x03600000      0
> 
> active partition: nor0,0 - (U-Boot) 0x00100000 @ 0x00000000
> 
> Has part_info() to be called here too? What is the if_type?
> What are the devicepaths for these partitions?

You have good points.
MMC's hw partitions and mtd's "environment variable-based" partitions
are quite different from the rest of table-based software partitions
in terms of U-Boot block device implementation.
Both neither are handled by part_info() (under disk/* framework)
nor have dedicated "if_type's".

Even if we might have to address those issues at the end, I would like to
keep them out of my scope for now as it requires a lot of extra work.

# I wonder if we should support mtdparts partitions on U-Boot UEFI
# as it is a quite U-Boot specific feature.

-Takahiro Akashi


> Best regards
> 
> Heinrich
> 
> >   #endif
> > 
> >   cleanup:
> >