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

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Mon, 1 Feb 2021 at 20:09, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>>
>> Peter Maydell <peter.maydell@linaro.org> writes:
>>
>> > 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-
>
>> Building a current Linux kernel with ``multi_v7_defconfig`` should be
>> enough to get something running. Nowadays an out-of-tree build is
>> recommended (and also useful if you build a lot of different targets).
>> $SRC points at root of the linux source tree.
>>
>> .. code-block:: bash
>>
>>   $ mkdir build; cd build
>>   $ make O=$(pwd) -C $SRC ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- multi_v7_defconfig
>>   $ make O=$(pwd) -C $SRC ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-
>
> That works, but do you really commonly cd into the build directory?
> I usually sit in the source tree...

Lets just be explicit and teach the user to fish:

Building a current Linux kernel with ``multi_v7_defconfig`` should be
enough to get something running. Nowadays an out-of-tree build is
recommended (and also useful if you build a lot of different targets).
In the following example $BLD points to the build directory and $SRC
points to the root of the Linux source tree. You can drop $SRC if you
are running from there.

.. code-block:: bash

  $ make O=$BLD -C $SRC ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- multi_v7_defconfig
  $ make O=$BLD -C $SRC ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-

>
> thanks
> -- PMM


-- 
Alex Bennée