On 9/14/25 14:46, Jan Kiszka wrote:
From: Jan Kiszka <jan.kis...@siemens.com>Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> Reviewed-by: Alex Bennée <alex.ben...@linaro.org> --- docs/system/device-emulation.rst | 1 + docs/system/devices/emmc.rst | 52 ++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+) create mode 100644 docs/system/devices/emmc.rst diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst index 911381643f..36429b1d17 100644 --- a/docs/system/device-emulation.rst +++ b/docs/system/device-emulation.rst @@ -101,3 +101,4 @@ Emulated Devices devices/canokey.rst devices/usb-u2f.rst devices/igb.rst + devices/emmc.rst diff --git a/docs/system/devices/emmc.rst b/docs/system/devices/emmc.rst new file mode 100644 index 0000000000..dbea6d6c7e --- /dev/null +++ b/docs/system/devices/emmc.rst @@ -0,0 +1,52 @@ +============== +eMMC Emulation +============== + +Besides SD card emulation, QEMU also offers an eMMC model as found on many +embedded boards. An eMMC, just like an SD card, is connected to the machine +via an SDHCI controller. + +Create eMMC Images +================== + +A recent eMMC consists of 4 partitions: 2 boot partitions, 1 Replay protected +Memory Block (RPMB), and the user data area. QEMU expects backing images for +the eMMC to contain those partitions concatenated in exactly that order. +However, the boot partitions as well as the RPMB might be absent if their sizes +are configured to zero. + +The eMMC specification defines alignment constraints for the partitions. The +two boot partitions must be of the same size. Furthermore, boot and RPMB +partitions must be multiples of 128 KB with a maximum of 32640 KB for each +boot partition and 16384K for the RPMB partition. + +The alignment constrain of the user data area depends on its size. Up to 2 +GByte, the size must be a power of 2. From 2 GByte onward, the size has to be +multiples of 512 byte. + +QEMU is enforcing those alignment rules before instantiating the device. +Therefore, the provided image has to strictly follow them as well. The helper +script `scripts/mkemmc.sh` can be used to create compliant images, with or
the single backquote would interpret scripts/mkemmc.sh as a ref. I think you want ``scripts/mkemmc.sh``
+without pre-filled partitions. E.g., to create an eMMC image from a firmware +image and an OS image with an empty 2 MByte RPMB, use the following command: + +.. code-block:: console + + scripts/mkemmc.sh -b firmware.img -r /dev/zero:2MB os.img emmc.img + +This will take care of rounding up the partition sizes to the next valid value +and will leave the RPMB and the second boot partition empty (zeroed). + +Adding eMMC Devices +=================== + +An eMMC is either automatically created by a machine model (e.g. Aspeed boards) +or can be user-created when using a PCI-attached SDHCI controller. To +instantiate the eMMC image from the example above while assuming that the +firmware needs a boot partitions of 1 MB, use the following options: + +.. code-block:: console + + -drive file=emmc.img,if=none,format=raw,id=emmc-img + -device sdhci-pci + -device emmc,drive=emmc-img,boot-partition-size=1048576,rpmb-partition-size=2097152
I will see if I can adjust the existing aspeed test with your proposal. Thanks, C.
