Re: [PATCH] hw/sd/sdcard: Allow user creation of eMMCs

["Jan Lübbe" <jlu@pengutronix.de>]

On Tue, 2024-10-29 at 15:06 +0000, Peter Maydell wrote:
> On Fri, 18 Oct 2024 at 16:42, Peter Maydell <peter.maydell@linaro.org> wrote:
> > On Tue, 15 Oct 2024 at 14:57, Jan Luebbe <jlu@pengutronix.de> wrote:
> > > For testing eMMC-specific functionality (such as handling boot
> > > partitions), it would be very useful to attach them to generic VMs such
> > > as x86_64 via the sdhci-pci device:
> > >  ...
> > >  -drive if=none,id=emmc-drive,file=emmc.img,format=raw \
> > >  -device sdhci-pci \
> > >  -device emmc,id=emmc0,drive=emmc-drive,boot-partition-size=1048576 \
> > >  ...
> > > 
> > > While most eMMCs are soldered to boards, they can also be connected to
> > > SD controllers with just a passive adapter, such as:
> > >  https://docs.radxa.com/en/accessories/emmc-to-usd
> > >  https://github.com/voltlog/emmc-wfbga153-microsd
> > > 
> > > The only change necessary to make the options above work is to avoid
> > > disabling user_creatable, so do that. The SDHCI-PCI driver in the Linux
> > > kernel already supports this just fine.
> > > 
> > > Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
> > 
> > Applied to target-arm.next, thanks (unless anybody would
> > prefer it to go via some other route).
> 
> I'm dropping this from target-arm.next since it seems like
> we have a problem with the handling of boot partitions
> and how the user should provide an image for an emmc card
> that has boot partitions). Since that's an emmc specific
> thing, sorting that out with a minimum of breaking
> compatibility with previously working setups is going to
> be easier if we stay temporarily in the state of "emmc
> only happens for the specific board that creates them
> and the user can't arbitrarily create them on the
> command line".
> 
> I expect this to just be a temporary delay while we sort
> out in the other thread how emmc boot partitions should work.

With Cédric's e8f3acdbb8 ("aspeed: Don't set always boot properties of the emmc
device") and my c078298301 ("hw/sd/sdcard: Fix calculation of size when using
eMMC boot partitions") in master, compatibility for existing setups should be
taken care of.

As mentioned in Cédric's patch, allowing user creatable eMMC devices is still
desirable. With my patch, that would work for machines where the SD controller
is user-created as well (e.g. x86_64 with sdhci-pci).

For machines where the SD controller and SD/eMMC are pre-created, additional
changes seem to be needed. Would you consider taking this patch to solve the
simple case first?

Thanks,
Jan
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