How to use lvgl on pc386 BSP.

Joel Sherrill joel at
Sun Sep 20 00:21:40 UTC 2020

On Sat, Sep 19, 2020, 4:42 PM Karel Gardas <karel.gardas at> wrote:

> On 9/19/20 10:32 AM, Christian Mauderer wrote:
> > Hello Karel,
> >
> > I wasn't aware that there is a framebuffer driver in the PC BSP.
> Yes, in fact there are three FB drivers in pc386 BSP family:
> - for VGA card
> - for Cirrus Logic GD5446 card
> - for VESA BIOS Extension capable graphics card
> The latest one is enabled by default and that's what I'm trying to use.
> > Maybe
> > an alternative to using the BSP framebuffer driver could be to just port
> > the FreeBSD framebuffer driver for PC and use that one? That might could
> > be less work than fixing the PC BSPs driver.
> Hmm. Just a brief check reveals that FB also supports several FB drivers:
> - for EFI frame buffer
> - for KMS enabled graphics card with vt_fb backend
> The former seems to be available on UEFI based systems only. The later
> seems to depends on DRM code which is *huge*. I've just meassured drm
> code from OpenBSD and this is more code than whole RTEMS kernel.
> (git:// and that just implementing DRM for Intel
> and AMD cards...
> In comparison with that pc386 fbs are light weight.
> Also FreeBSD vga driver which supports VESA BIOS Extensions does not
> seems to enable framebuffer...
> > If you want to continue to use the BSPs driver, I can try to have a more
> > detailled look at it.
> I think I can also do something as I do have setup here -- just try to
> debug into mmap to see why it's not able to mmap /dev/fd0 and this way
> get more info about the failure...

Gedare wrote the current POSIX shm and mmap support. I know it has a plugin
architecture to enable mapping shared memory between partitions in
Does+RTEMS. It could be as simple as the device file type in the IMFS is
defaulting a file operation it needs to support.

Start a separate thread with a more specific subject and Gedare will
probably pipe up.

> > But like I said: I would expect that the FreeBSD
> > driver is simpler to use.
> I'm not so sure, see above, but please correct me if I'm wrong since
> especially I'm expert on neither FBSD, frame buffers and C...
> Thanks,
> Karel
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