On 02/21/2018 05:39 PM, Farhan Ali wrote: > > > On 02/21/2018 07:11 AM, Christian Borntraeger wrote: >> >> >> On 02/21/2018 01:07 PM, Cornelia Huck wrote: >> [...] >>>>> But if you need to enable PCI to get IOMEM, I wonder why this patch here >>>>> is needed at all? The Graphics menu / VT dummy console should be >>>>> available in the config if IOMEM is enabled anyway? >>>> >>>> That is a good question. With CONFIG_PCI=y I can select virtio-gpu and >>>> dummy-console. >>>> IIRC the issue was that with patch 3 we can have the situation where we >>>> have >>>> CONFIG_VT = y and CONFIG_DUMMY_CONSOLE=n and this will crash early during >>>> boot as >>>> conswitchp is NULL. > > Yes, VT layer initializes very early in the boot process and looks for a > console. If it can't find any it will crash. I believe that was the whole > point of having the dummy console. > >>> >>> So in practice, CONFIG_VT depends on "there's a console available, even >>> if it's only the dummy one"? >> >> Yes. Maybe we should simple move dummy_console outside of >> drivers/video/console/Kconfig >> into something that is always available. >> > > I agree, but where should it go? consoles are kinda tightly tied to > video/Graphics Support. > >>> >>>> This patches goal was to always enable dummy console even without >>>> PCI, but it obviously fails to do so. >>> > This patch should enable the dummy console even without PCI but we won't have > DRM/Virtio GPU.
All right. This patch then makes sure that VT does not crash since it guarantees that DUMMY_CONSOLE is available. If the user want to have virtio-gpu it needs to enable PCI due to the dependencies, but this is a different issue that we can fix later. So the patch is fine as long as you take care of these things - add missing HAS_IOMEM dependency to VGA_CONSOLE - extend "if HAS_IOMEM" in drivers/video/Kconfig to cover config items previously covered by this dependency (it should start before config HAVE_FB_ATMEL and end after config HDMI) as requested by Bartlomiej
