On Mon, Nov 22, 2021 at 11:11:11PM -0500, Vivien Didelot wrote: > Hi Denys, > > On Mon, 22 Nov 2021 13:26:07 -0500 "Denys Dmytriyenko" <de...@denix.org> > wrote: > > On Sat, Nov 20, 2021 at 03:00:05PM -0500, Vivien Didelot wrote: > > > Hi Denys, > > > > > > On Fri, 19 Nov 2021 22:02:11 -0500 "Denys Dmytriyenko" <de...@denix.org> > > > wrote: > > > > On Fri, Nov 19, 2021 at 03:15:33PM -0500, Vivien Didelot wrote: > > > > > Some distros or image recipes may rely on the presence of the "screen" > > > > > machine feature to install graphical front-end applications. > > > > > > > > > > The ti33x SoC has an integrated GPU but does not have a screen per-se, > > > > > thus having this feature in the SoC configuration may lead to unwanted > > > > > packages being built. > > > > > > > > > > Comment the 'screen' feature and remove it from MACHINE_FEATURES. > > > > > > > > Well, 'screen' also implies not just a built-in LCD, but also external > > > > screens > > > > connected over HDMI or DVI. There are even remnant MACHINE_GUI_CLASS > > > > variables > > > > set in machine configs for either "bigscreen" or "smallscreen", > > > > although that > > > > one is no longer used. > > > > > > I understand what you're saying. The confusion comes from the fact that > > > some people think about the 'screen' feature as 'the machine has an LCD > > > _controller_ and/or graphic output port(s)', while others think of it as > > > 'the machine literally has a graphical display'. > > > > It is as simple as whether the machine is headless or not. > > > > > > > IMHO the 'screen' and 'touchscreen' machine features are a > > > software-agnostic > > > way to describe the usage of a physical graphical display on the end > > > product; > > > > > > the 'directfb', 'x11' and 'wayland' distro features are a subjective way > > > to configure the graphical software stack of choice; > > > > > > and finally the 'gpu' machine feature describes the capability of hardware > > > accelerated graphical processing. > > > > Well, 'gpu' is not an upstream MACHINE_FEATURE, as BSPs can define > > additional > > ones for own use. It used to be 'sgx', but with the addition of Rogue RGX > > graphics, got renamed to more generic 'gpu': > > https://git.yoctoproject.org/cgit/cgit.cgi/meta-ti/commit/?id=0d9910c1710d9d4b2dd986403824ae05b6289e63 > > > > BTW, a display output (screen) can be very different and independent from a > > 3D > > processing (gpu), hence those are 2 separate features. > > > > > > > As an example, a distro can configure the Qt stack and tweak images like > > > this: > > > > > > DISTRO_FEATURES:append = " directfb" > > > PACKAGECONFIG_DISTRO:pn-qtbase ?= " \ > > > ${@bb.utils.contains('MACHINE_FEATURES', 'gpu', 'eglfs', '', d)} \ > > > ${@bb.utils.contains('MACHINE_FEATURES', 'touchscreen', 'libinput > > > tslib', '', d)} \ > > > " > > > EXTRA_IMAGE_FEATURES ?= " \ > > > ${@bb.utils.contains('MACHINE_FEATURES', 'gpu', 'hwcodecs', '', > > > d)} \ > > > ${@bb.utils.contains_any('MACHINE_FEATURES', 'screen > > > touchscreen', 'splash', '', d)} \ > > > " > > > > > > while a generic image recipe or local conf can tweak packages this: > > > > > > IMAGE_INSTALL:append = " ${@bb.utils.contains_any('MACHINE_FEATURES', > > > 'screen touchscreen', 'qt-kiosk-browser', '', d)}" > > > > > > The MACHINE_GUI_CLASS actually shares the same concern, it assumes the > > > presence of a built-in screen of subjective size, which is simply wrong > > > for machines with an optional graphical display. > > > > MACHINE_GUI_CLASS was used more widely in the past, but these days it only > > affects the size of the logo in kernel boot when linux.inc from meta-oe is > > included, which again is not used in meta-ti: > > https://git.openembedded.org/meta-openembedded/tree/meta-oe/recipes-kernel/linux/linux.inc#n19 > > > > > > > > All TI platforms with am335x SoC do have screen outputs, but I do > > > > understand > > > > there could be headless platforms from other manufacturers with this > > > > SoC. The > > > > correct way would be to not completely remove "screen" MACHINE_FEATURE > > > > from > > > > the SoC include file, but rather move it to corresponding machine > > > > configs that > > > > use it - am335x-evm, beaglebone, etc. > > > > > > I would say that the 'screen' feature definitely doesn't belong to the SoC > > > configuration, and it doesn't belong to the machine description neither: > > > > > > even though I understand it can be handy for beginners, boards like Rpi > > > and BeagleBone can be used headless and thus removing the feature from the > > > local configuration to get rid of unwanted configs is likewise cumbersome. > > > > > > I think it's the user responsibility to specify MACHINE_FEATURES += > > > "screen" > > > in their local configuration to describe the usage of a graphical display, > > > especially for machines not shipped with a built-in one. > > > > That's not how it works! > > > > All available MACHINE_FEATURES are defined in machine config files. Think > > of > > those as capabilities. The list defines what this specific machine is > > capable > > of, but it's up to you to use it or not. > > > > That's no different from the rest of them, such as: > > acpi, alsa, apm, ext2, ext3, vfat, screen, keyboard, touchscreen, pci, > > pcmcia, > > phone, serial, usbgadget, usbhost, bluetooth, wifi, x86, kernel26... > > > > Note that some of them are really software capabilities, but historically > > were specified in machine configs. And kernel26 has been dropped long ago, > > but is still lingering in places... > > > > A distro config, or an image recipe, or even end user via local.conf can > > decide whether to act on those capabilities or not. E.g. It doesn't matter > > if > > a machine can support 'alsa' audio if you don't need any audio in your > > image, > > you simply do not install corresponding packages. > > > > There are 2 very different approaches. 1) When you are building a reference > > distro and try to be very flexible and do a lot of conditionals based on > > capabilities and features. And 2) when you are making a final product for a > > specific platform, where pretty much everything is predetermined and static. > > > > So, if you are making a product, your image recipe should not rely on > > checking > > available capabilities or features that much, if at all... > > Are you suggesting that one must write MACHINE_FEATURES:remove = "screen" > if their machine is headless (which is the case for a stock BeagleBone)?
Beagles are not headless - most of BeagleBoards and BeagleBones have either HDMI, micro-HDMI, DVI-D or can be outfitted with a corresponding cape. I was suggesting to move "screen" MACHINE_FEATURE from a generic SoC config to corresponding machine configs. -- Regards, Denys Dmytriyenko <de...@denix.org> PGP: 0x420902729A92C964 - https://denix.org/0x420902729A92C964 Fingerprint: 25FC E4A5 8A72 2F69 1186 6D76 4209 0272 9A92 C964
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