Re: [PATCH] docs/system: document an example vexpress-a15 invocation

[Peter Maydell]

On Thu, 28 Jan 2021 at 18:53, Alex Bennée <alex.bennee@linaro.org> wrote:
>
> The wiki and the web are curiously absent of the right runes to boot a
> vexpress model so I had to work from first principles to work it out.
> Use the more modern -drive notation so alternative backends can be
> used (unlike the hardwired -sd mode).
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Anders Roxell <anders.roxell@linaro.org>
> ---
>  docs/system/arm/vexpress.rst | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/docs/system/arm/vexpress.rst b/docs/system/arm/vexpress.rst
> index 7f1bcbef07..30b1823b95 100644
> --- a/docs/system/arm/vexpress.rst
> +++ b/docs/system/arm/vexpress.rst
> @@ -58,3 +58,29 @@ Other differences between the hardware and the QEMU model:
>    ``vexpress-a15``, and have IRQs from 40 upwards. If a dtb is
>    provided on the command line then QEMU will edit it to include
>    suitable entries describing these transports for the guest.
> +
> +Booting a Linux kernel
> +----------------------
> +
> +Building a current Linux kernel with ``multi_v7_defconfig`` should be
> +enough to get something running.
> +
> +.. code-block:: bash
> +
> +  $ export ARCH=arm
> +  $ export CROSS_COMPILE=arm-linux-gnueabihf-
> +  $ make multi_v7_defconfig
> +  $ make

We probably shouldn't be recommending in-tree kernel builds, or
polluting the user's environment with random variables. Try:

$ make O=builddir ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- multi_v7_defconfig
$ make O=builddir ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

> +By default you will want to boot your rootfs of the sdcard interface.

"off"

> +Your rootfs will need to be padded to the right size. With a suitable
> +DTB you could also add devices to the virtio-mmio bus.
> +
> +.. code-block:: bash
> +
> +  $ qemu-system-arm -cpu cortex-a15 -smp 4 -m 4096 \
> +      -machine type=vexpress-a15 -serial mon:stdio \
> +      -drive if=sd,driver=file,filename=armel-rootfs.ext4 \
> +      -kernel zImage  \
> +      -dtb vexpress-v2p-ca15-tc1.dtb \
> +      -append "console=ttyAMA0 root=/dev/mmcblk0 ro"

thanks
-- PMM