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

[Peter Maydell <peter.maydell@linaro.org>]

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...

thanks
-- PMM