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Re: [PATCH] docs/system: riscv: Update Microchip Icicle Kit for direct k


From: Alistair Francis
Subject: Re: [PATCH] docs/system: riscv: Update Microchip Icicle Kit for direct kernel boot
Date: Thu, 8 Jul 2021 14:49:46 +1000

On Tue, Jul 6, 2021 at 7:50 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> From: Bin Meng <bin.meng@windriver.com>
>
> 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>

Alistair

> ---
>
>  docs/system/riscv/microchip-icicle-kit.rst | 54 +++++++++++++++++++---
>  1 file changed, 47 insertions(+), 7 deletions(-)
>
> diff --git a/docs/system/riscv/microchip-icicle-kit.rst 
> b/docs/system/riscv/microchip-icicle-kit.rst
> index 54ced661e3..817d2aec9c 100644
> --- a/docs/system/riscv/microchip-icicle-kit.rst
> +++ b/docs/system/riscv/microchip-icicle-kit.rst
> @@ -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
> --
> 2.25.1
>
>



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