Commit 25840030 authored Feb 22, 2018 by Farhan Ali Committed by Christian Borntraeger Mar 14, 2018

s390/setup: enable display support for KVM guest



The S390 architecture does not support any graphics hardware,
but with the latest support for Virtio GPU in Linux and Virtio
GPU emulation in QEMU, it's possible to enable graphics for
S390 using the Virtio GPU device.

To enable display we need to enable the Linux Virtual Terminal (VT)
layer for S390. But the VT subsystem initializes quite early
at boot so we need a dummy console driver till the Virtio GPU
driver is initialized and we can run the framebuffer console.

The framebuffer console over a Virtio GPU device can be run
in combination with the serial SCLP console (default on S390).
The SCLP console can still be accessed by management applications
(eg: via Libvirt's virsh console).

Signed-off-by: Farhan Ali <alifm@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <e23b61f4f599ba23881727a1e8880e9d60cc6a48.1519315352.git.alifm@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent daea5469

arch/s390/kernel/setup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -221,6 +221,8 @@ static void __init conmode_default(void)
		SET_CONSOLE_SCLP;
		#endif
		}
		if (IS_ENABLED(CONFIG_VT) && IS_ENABLED(CONFIG_DUMMY_CONSOLE))
		conswitchp = &dummy_con;
		}

		#ifdef CONFIG_CRASH_DUMP

drivers/tty/Kconfig

+1 −1

Original line number	Diff line number	Diff line
		@@ -11,7 +11,7 @@ if TTY

		config VT
		bool "Virtual terminal" if EXPERT
		depends on !S390 && !UML
		depends on !UML
		select INPUT
		default y
		---help---

drivers/video/console/Kconfig

+1 −1

Original line number	Diff line number	Diff line
		@@ -9,7 +9,7 @@ config VGA_CONSOLE
		depends on !4xx && !PPC_8xx && !SPARC && !M68K && !PARISC && !FRV && \
		!SUPERH && !BLACKFIN && !AVR32 && !MN10300 && !CRIS && \
		(!ARM \|\| ARCH_FOOTBRIDGE \|\| ARCH_INTEGRATOR \|\| ARCH_NETWINDER) && \
		!ARM64 && !ARC && !MICROBLAZE && !OPENRISC && HAS_IOMEM
		!ARM64 && !ARC && !MICROBLAZE && !OPENRISC && HAS_IOMEM && !S390
		default y
		help
		Saying Y here will allow you to use Linux in text mode through a

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