On Sat, Dec 05, 2020 at 09:05:16PM +0100, Enrico Weigelt, metux IT consult wrote: > On 05.12.20 20:32, Michael S. Tsirkin wrote: > > Hi, > > > It seems a bit of a mess, at this point I'm not entirely sure when > > should drivers select VIRTIO and when depend on it. > > if VIRTIO just enables something that could be seen as library > functions, then select should be right, IMHO. > > > The text near it says: > > > > # SPDX-License-Identifier: GPL-2.0-only > > config VIRTIO > > tristate > > oh, wait, doesn't have an menu text, so we can't even explicitly enable > it (not shown in menu) - only implicitly. Which means that some other > option must select it, in order to become availe at all, and in order > to make others depending on it becoming available. > > IMHO, therefore select is the correct approach. > > > > help > > This option is selected by any driver which implements the virtio > > bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG > > or CONFIG_S390_GUEST. > > > > Which seems clear enough and would indicate drivers for devices *behind* > > the bus should not select VIRTIO and thus presumably should "depend on" it. > > This is violated in virtio console and virtio fs drivers. > > See above: NAK. because it can't even be enabled directly (by the user). > If it wasn't meant otherwise, we'd have to add an menu text. The point is that user enables one of the bindings. That in turn enables drivers. If we merely select VIRTIO there's a chance user won't remember to select any bindings and will be surprised not to see any devices. > > For console it says: > > > > commit 9f30eb29c514589e16f2999ea070598583d1f6ec > > Author: Michal Suchanek <msuchanek@xxxxxxx> > > Date: Mon Aug 31 18:58:50 2020 +0200 > > > > char: virtio: Select VIRTIO from VIRTIO_CONSOLE. > > > > Make it possible to have virtio console built-in when > > other virtio drivers are modular. > > > > Signed-off-by: Michal Suchanek <msuchanek@xxxxxxx> > > Reviewed-by: Amit Shah <amit@xxxxxxxxxx> > > Link: https://lore.kernel.org/r/20200831165850.26163-1-msuchanek@xxxxxxx > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > which seems kind of bogus - why do we care about allowing a builtin > > virtio console driver if the pci virtio bus driver is a module? > > There won't be any devices on the bus to attach to ... > > When using other transports ? Any transport selects VIRTIO so if you enable that, you get VIRTIO and thus it's enough to depend on it. > In my current project, eg. I'm using mmio - my kernel has pci completely > disabled. > > > I am inclined to fix console and virtio fs to depend on VIRTIO: > > select is harder to use correctly ... > > I don't thinkt that would be good - instead everybody should just select > VIRTIO, never depend on it (maybe depend on VIRTIO_MENU instead) GPU depends on VIRTIO and on VIRTIO_MENU ... which seems even messier ... > > --mtx > > -- > --- > Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert > werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren > GPG/PGP-Schlüssel zu. > --- > Enrico Weigelt, metux IT consult > Free software and Linux embedded engineering > info@xxxxxxxxx -- +49-151-27565287
