From: "Michal Suchánek" <msuchanek@suse.de>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "Enrico Weigelt, metux IT consult" <lkml@metux.net>,
Jason Wang <jasowang@redhat.com>,
"Enrico Weigelt, metux IT consult" <info@metux.net>,
linux-kernel@vger.kernel.org, corbet@lwn.net,
linus.walleij@linaro.org, bgolaszewski@baylibre.com,
linux-doc@vger.kernel.org, linux-gpio@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-riscv@lists.infradead.org, stefanha@redhat.com
Subject: Re: [PATCH v2 2/2] drivers: gpio: add virtio-gpio guest driver
Date: Tue, 8 Dec 2020 11:10:51 +0100 [thread overview]
Message-ID: <20201208101051.GC6564@kitsune.suse.cz> (raw)
In-Reply-To: <20201205142218-mutt-send-email-mst@kernel.org>
Hello
On Sat, Dec 05, 2020 at 02:32:04PM -0500, Michael S. Tsirkin wrote:
> On Sat, Dec 05, 2020 at 08:59:55AM +0100, Enrico Weigelt, metux IT consult wrote:
> > On 04.12.20 04:35, Jason Wang wrote:
> >
> > >
> > > Let's use select, since there's no prompt for VIRTIO and it doesn't have
> > > any dependencies.
> >
> > whoops, it's not that simple:
> >
> > make: Entering directory '/home/nekrad/src/apu2-dev/pkg/kernel.apu2.git'
> > make[1]: Entering directory
> > '/home/nekrad/src/dk/DistroKit/platform-x86_64/build-target/linux-5.8.9-build'
> > GEN Makefile
> > drivers/gpu/drm/Kconfig:74:error: recursive dependency detected!
> > drivers/gpu/drm/Kconfig:74: symbol DRM_KMS_HELPER is selected by
> > DRM_VIRTIO_GPU
> > drivers/gpu/drm/virtio/Kconfig:2: symbol DRM_VIRTIO_GPU depends on VIRTIO
> > drivers/virtio/Kconfig:2: symbol VIRTIO is selected by GPIO_VIRTIO
> > drivers/gpio/Kconfig:1618: symbol GPIO_VIRTIO depends on GPIOLIB
> > drivers/gpio/Kconfig:14: symbol GPIOLIB is selected by I2C_MUX_LTC4306
> > drivers/i2c/muxes/Kconfig:47: symbol I2C_MUX_LTC4306 depends on I2C
> > drivers/i2c/Kconfig:8: symbol I2C is selected by FB_DDC
> > drivers/video/fbdev/Kconfig:63: symbol FB_DDC depends on FB
> > drivers/video/fbdev/Kconfig:12: symbol FB is selected by DRM_KMS_FB_HELPER
> > drivers/gpu/drm/Kconfig:80: symbol DRM_KMS_FB_HELPER depends on
> > DRM_KMS_HELPER
> >
> > Seems that we can only depend on or select some symbol - we run into
> > huge trouble if thats mixed. Just changed DRM_VIRTIO_GPU to just select
> > VIRIO instead of depending on it, and now it works.
> >
> > I've posted another patch for fixing drivers/gpu/drm/virtio/Kconfig
> > to use 'select' instead of 'depends on'.
>
> 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.
>
> The text near it says:
>
> # SPDX-License-Identifier: GPL-2.0-only
> config VIRTIO
> tristate
> 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.
>
> For console it says:
>
> commit 9f30eb29c514589e16f2999ea070598583d1f6ec
> Author: Michal Suchanek <msuchanek@suse.de>
> 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@suse.de>
> Reviewed-by: Amit Shah <amit@kernel.org>
> Link: https://lore.kernel.org/r/20200831165850.26163-1-msuchanek@suse.de
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> 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 ...
The console driver provides early console which should initialize
without any transport. I have not tested it actually works but the code
seems to be there to support this use case.
Thanks
Michal
next prev parent reply other threads:[~2020-12-08 10:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 19:11 [PATCH v2 1/2] drivers: gpio: put virtual gpio device into their own submenu Enrico Weigelt, metux IT consult
2020-12-03 19:11 ` [PATCH v2 2/2] drivers: gpio: add virtio-gpio guest driver Enrico Weigelt, metux IT consult
2020-12-04 3:35 ` Jason Wang
2020-12-04 9:36 ` Enrico Weigelt, metux IT consult
2020-12-07 3:48 ` Jason Wang
2020-12-07 9:33 ` Enrico Weigelt, metux IT consult
2020-12-08 2:49 ` Jason Wang
2021-04-13 11:07 ` Alex Bennée
2020-12-05 7:59 ` Enrico Weigelt, metux IT consult
2020-12-05 19:32 ` Michael S. Tsirkin
2020-12-05 20:05 ` Enrico Weigelt, metux IT consult
2020-12-07 3:16 ` Jason Wang
2020-12-07 13:52 ` Michael S. Tsirkin
2020-12-07 20:34 ` Enrico Weigelt, metux IT consult
2020-12-07 3:12 ` Jason Wang
2020-12-07 13:53 ` Michael S. Tsirkin
2020-12-08 2:36 ` Jason Wang
2020-12-08 7:02 ` Enrico Weigelt, metux IT consult
2020-12-09 9:31 ` Jason Wang
2020-12-09 10:33 ` Enrico Weigelt, metux IT consult
2020-12-08 10:10 ` Michal Suchánek [this message]
2020-12-08 12:33 ` Enrico Weigelt, metux IT consult
2020-12-09 10:34 ` Michal Suchánek
2020-12-05 20:15 ` Howto listen to/handle gpio state changes ? " Enrico Weigelt, metux IT consult
2020-12-08 9:38 ` Linus Walleij
2020-12-08 14:04 ` Enrico Weigelt, metux IT consult
2020-12-08 16:15 ` Grygorii Strashko
2020-12-09 8:51 ` Linus Walleij
2020-12-09 11:19 ` Arnd Bergmann
2020-12-09 12:53 ` Linus Walleij
2020-12-09 20:22 ` Grygorii Strashko
2020-12-09 20:38 ` Arnd Bergmann
2020-12-10 13:32 ` Grygorii Strashko
2021-05-24 11:27 ` Viresh Kumar
2021-05-25 12:59 ` Enrico Weigelt, metux IT consult
2021-05-26 3:32 ` Viresh Kumar
2021-07-03 8:05 ` Michael S. Tsirkin
2021-07-05 3:51 ` Viresh Kumar
2020-12-07 9:55 ` [PATCH v2 1/2] drivers: gpio: put virtual gpio device into their own submenu Andy Shevchenko
2020-12-07 10:31 ` Bartosz Golaszewski
2020-12-07 11:22 ` Enrico Weigelt, metux IT consult
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