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docs/system: riscv: Update Microchip Icicle Kit for direct kernel boot 

This adds a new section in the documentation to demonstrate how to
use the new direct kernel boot feature for Microchip Icicle Kit,
other than the HSS bootflow, using an upstream U-Boot v2021.07 image
as an example.

It also updates the truth table to have a new '-dtb' column which is
required by direct kernel boot.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20210706095045.1917913-1-bmeng.cn@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Bin Meng 2021-07-06 17:50:45 +08:00 committed by Alistair Francis
parent bc083a51ca
commit 6165dcb55f
1 changed files with 47 additions and 7 deletions
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54
docs/system/riscv/microchip-icicle-kit.rst
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@ -47,13 +47,13 @@ The user provided DTB should have the following requirements:
QEMU follows below truth table to select which payload to execute:
===== ========== =======
-bios -kernel payload
===== ========== =======
N N HSS
Y don't care HSS
N Y kernel
===== ========== =======
===== ========== ========== =======
-bios -kernel -dtb payload
===== ========== ========== =======
N N don't care HSS
Y don't care don't care HSS
N Y Y kernel
===== ========== ========== =======
The memory is set to 1537 MiB by default which is the minimum required high
memory size by HSS. A sanity check on ram size is performed in the machine
@ -106,4 +106,44 @@ HSS output is on the first serial port (stdio) and U-Boot outputs on the
second serial port. U-Boot will automatically load the Linux kernel from
the SD card image.
Direct Kernel Boot
------------------
Sometimes we just want to test booting a new kernel, and transforming the
kernel image to the format required by the HSS bootflow is tedious. We can
use '-kernel' for direct kernel booting just like other RISC-V machines do.
In this mode, the OpenSBI fw_dynamic BIOS image for 'generic' platform is
used to boot an S-mode payload like U-Boot or OS kernel directly.
For example, the following commands show building a U-Boot image from U-Boot
mainline v2021.07 for the Microchip Icicle Kit board:
.. code-block:: bash
$ export CROSS_COMPILE=riscv64-linux-
$ make microchip_mpfs_icicle_defconfig
Then we can boot the machine by:
.. code-block:: bash
$ qemu-system-riscv64 -M microchip-icicle-kit -smp 5 -m 2G \
-sd path/to/sdcard.img \
-nic user,model=cadence_gem \
-nic tap,ifname=tap,model=cadence_gem,script=no \
-display none -serial stdio \
-kernel path/to/u-boot/build/dir/u-boot.bin \
-dtb path/to/u-boot/build/dir/u-boot.dtb
CAVEATS:
* Check the "stdout-path" property in the /chosen node in the DTB to determine
which serial port is used for the serial console, e.g.: if the console is set
to the second serial port, change to use "-serial null -serial stdio".
* The default U-Boot configuration uses CONFIG_OF_SEPARATE hence the ELF image
``u-boot`` cannot be passed to "-kernel" as it does not contain the DTB hence
``u-boot.bin`` has to be used which does contain one. To use the ELF image,
we need to change to CONFIG_OF_EMBED or CONFIG_OF_PRIOR_STAGE.
.. _HSS: https://github.com/polarfire-soc/hart-software-services