Write the BSP for ARM Versatile Express device

[Đức Anh]

Hi Gedare,

For the last few days, I am reading the rtems source code, trying to
understand the build system, how a bsp is built. I just has a few questions:
- it seems like the configure.ac and Makefile.am for each BSP
(c/src/lib/libbsp/) is separate from the BSP source code (bsps/). However
not all BSP has configure.ac and Makefile.am, for example, the FVP BSP you
said. What is the difference here?
- my speculation right now is to create a new folder in c/src/lib/libbsp/
for the VExpress device, put the configure.ac and Makefile.am in and put
the source file in bsps/ ?

Best regards,
Duc Anh


Vào Th 4, 14 thg 4, 2021 vào lúc 12:53 Gedare Bloom <gedare at rtems.org> đã
viết:

> Hi Duc,
>
> On Tue, Apr 13, 2021 at 8:57 AM Đức Anh <dauto98 at gmail.com> wrote:
> >
> > Dear all,
> >
> > I want to develop a BSP for ARM Versatile Express platform. My final
> purpose is to run Gem5 simulation using RTEMS as the kernel. Now Gem5 only
> model Versatile Express device, and I can see RTEMS does not have a BSP for
> it yet.
> >
> > More specifically, the machine type modelled in Gem5 is:
> > - Arm Motherboard Express uATX (V2M-P1)
> > - The memory map is based on Versatile Express RS1, with RS2 extension
> > - Arm CoreTile Express A15x2 (V2P-CA15) as daughterboard. It contains
> Cortex-A15 CPU.
> >
> > In the past, the Realview-pbx-a9 BSP used to run successfully in Gem5,
> when they still supported realview machine type. It is not the case now. So
> I guess I can reuse the CPU related code in realview-pbx-a9 and just write
> new code for the BSP ?
> >
> Well, the realview pbx a9 is a cortex-a9 device and not an a15. Plus,
> I guess the vexpress will have some differences in how it deals with
> interrupts and maybe messaging given its tiled architecture? I don't
> know too much about it. But, your best bet is probably to try to start
> with the FVP bsp, which was only added about 5 months ago and supports
> just a Cortex-R52 right now, but probably adding the vexpress RS1
> memory map with the V2P-CA15 is the right way for you to go.
>
> > I am new to RTEMS so I need some help. Which direction should I head for?
> >
> Join the devel at rtems.org mailing list for technical email discussions
> regarding hacking within RTEMS proper. (The "users" mailing list is a
> bit more for people trying to develop/maintain their application
> software using RTEMS mostly *fingers crossed* out of the box.) I would
> strongly recommend that you get started by following through our
> tutorials to get a feel for the tools and development environment:
> https://docs.rtems.org/branches/master/user/start/index.html
> Read carefully and don't skip steps, or you probably miss something
> important that you won't figure out until a couple hours later and
> have to redo everything. Since you plan new development, you should
> use the `master` branch of RTEMS with the `master` branch of the
> rtems-source-builder to build your cross-compiler toolchain. This is
> referred to as version '6' although it is not yet a released version.
>
> Right now we have a lot of new faces on devel@ because of the Google
> Summer of Code, so you'll find a lot of other people with questions
> and answers about how to get started etc. I would recommend you also
> do our GSoC Getting Started part of the tutorial so that you can get
> some comfort with the developer workflow and how to make changes in
> RTEMS and see them in the recompiled version.
>
> Finally, for new BSP development, I guess you can start by having a
> look at https://docs.rtems.org/branches/master/bsp-howto/index.html
> This is an aging document, but still a good resource to understand the
> basic ideas about BSP implementation.
>
> -Gedare
>
> > Best regards,
> > Duc Anh
> > _______________________________________________
> > users mailing list
> > users at rtems.org
> > http://lists.rtems.org/mailman/listinfo/users
>
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