diff --git a/docs/system/arm/xlnx-versal-virt.rst b/docs/system/arm/xlnx-versal-virt.rst index 27f73500d9..92ad10d2da 100644 --- a/docs/system/arm/xlnx-versal-virt.rst +++ b/docs/system/arm/xlnx-versal-virt.rst @@ -32,6 +32,8 @@ Implemented devices: - OCM (256KB of On Chip Memory) - XRAM (4MB of on chip Accelerator RAM) - DDR memory +- BBRAM (36 bytes of Battery-backed RAM) +- eFUSE (3072 bytes of one-time field-programmable bit array) QEMU does not yet model any other devices, including the PL and the AI Engine. @@ -175,3 +177,50 @@ Run the following at the U-Boot prompt: fdt set /chosen/dom0 reg <0x00000000 0x40000000 0x0 0x03100000> booti 30000000 - 20000000 +BBRAM File Backend +"""""""""""""""""" +BBRAM can have an optional file backend, which must be a seekable +binary file with a size of 36 bytes or larger. A file with all +binary 0s is a 'blank'. + +To add a file-backend for the BBRAM: + +.. code-block:: bash + + -drive if=pflash,index=0,file=versal-bbram.bin,format=raw + +To use a different index value, N, from default of 0, add: + +.. code-block:: bash + + -global xlnx,bbram-ctrl.drive-index=N + +eFUSE File Backend +"""""""""""""""""" +eFUSE can have an optional file backend, which must be a seekable +binary file with a size of 3072 bytes or larger. A file with all +binary 0s is a 'blank'. + +To add a file-backend for the eFUSE: + +.. code-block:: bash + + -drive if=pflash,index=1,file=versal-efuse.bin,format=raw + +To use a different index value, N, from default of 1, add: + +.. code-block:: bash + + -global xlnx,efuse.drive-index=N + +.. warning:: + In actual physical Versal, BBRAM and eFUSE contain sensitive data. + The QEMU device models do **not** encrypt nor obfuscate any data + when holding them in models' memory or when writing them to their + file backends. + + Thus, a file backend should be used with caution, and 'format=luks' + is highly recommended (albeit with usage complexity). + + Better yet, do not use actual product data when running guest image + on this Xilinx Versal Virt board.