From: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
docs/system/device-emulation.rst | 1 +
docs/system/devices/emmc.rst | 53 ++++++++++++++++++++++++++++++++
2 files changed, 54 insertions(+)
create mode 100644 docs/system/devices/emmc.rst
diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst
index db714ad47a..971325527a 100644
--- a/docs/system/device-emulation.rst
+++ b/docs/system/device-emulation.rst
@@ -88,6 +88,7 @@ Emulated Devices
devices/canokey.rst
devices/ccid.rst
devices/cxl.rst
+ devices/emmc.rst
devices/igb.rst
devices/ivshmem-flat.rst
devices/ivshmem.rst
diff --git a/docs/system/devices/emmc.rst b/docs/system/devices/emmc.rst
new file mode 100644
index 0000000000..7e15b62270
--- /dev/null
+++ b/docs/system/devices/emmc.rst
@@ -0,0 +1,53 @@
+==============
+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
+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 in a machine without other
+SDHCI controllers 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
--
2.51.0
On 4/11/25 14:03, Jan Kiszka wrote: > From: Jan Kiszka <jan.kiszka@siemens.com> > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> > Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> > --- > docs/system/device-emulation.rst | 1 + > docs/system/devices/emmc.rst | 53 ++++++++++++++++++++++++++++++++ > 2 files changed, 54 insertions(+) > create mode 100644 docs/system/devices/emmc.rst > > diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst > index db714ad47a..971325527a 100644 > --- a/docs/system/device-emulation.rst > +++ b/docs/system/device-emulation.rst > @@ -88,6 +88,7 @@ Emulated Devices > devices/canokey.rst > devices/ccid.rst > devices/cxl.rst > + devices/emmc.rst > devices/igb.rst > devices/ivshmem-flat.rst > devices/ivshmem.rst > diff --git a/docs/system/devices/emmc.rst b/docs/system/devices/emmc.rst > new file mode 100644 > index 0000000000..7e15b62270 > --- /dev/null > +++ b/docs/system/devices/emmc.rst > @@ -0,0 +1,53 @@ I'll getting: WARNING: Does new file 'docs/system/devices/emmc.rst' need 'SPDX-License-Identifier'? Should I add (on your behalf): .. SPDX-License-Identifier: GPL-2.0-or-later ? > +============== > +eMMC Emulation > +============== > +
On 04.11.25 17:57, Philippe Mathieu-Daudé wrote: > On 4/11/25 14:03, Jan Kiszka wrote: >> From: Jan Kiszka <jan.kiszka@siemens.com> >> >> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> >> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> >> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> >> --- >> docs/system/device-emulation.rst | 1 + >> docs/system/devices/emmc.rst | 53 ++++++++++++++++++++++++++++++++ >> 2 files changed, 54 insertions(+) >> create mode 100644 docs/system/devices/emmc.rst >> >> diff --git a/docs/system/device-emulation.rst b/docs/system/device- >> emulation.rst >> index db714ad47a..971325527a 100644 >> --- a/docs/system/device-emulation.rst >> +++ b/docs/system/device-emulation.rst >> @@ -88,6 +88,7 @@ Emulated Devices >> devices/canokey.rst >> devices/ccid.rst >> devices/cxl.rst >> + devices/emmc.rst >> devices/igb.rst >> devices/ivshmem-flat.rst >> devices/ivshmem.rst >> diff --git a/docs/system/devices/emmc.rst b/docs/system/devices/emmc.rst >> new file mode 100644 >> index 0000000000..7e15b62270 >> --- /dev/null >> +++ b/docs/system/devices/emmc.rst >> @@ -0,0 +1,53 @@ > > I'll getting: > > WARNING: Does new file 'docs/system/devices/emmc.rst' need 'SPDX- > License-Identifier'? > > Should I add (on your behalf): > > .. SPDX-License-Identifier: GPL-2.0-or-later > > ? Yes, that license line is fine here. Jan -- Siemens AG, Foundational Technologies Linux Expert Center
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