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Date:      Wed, 14 Mar 2018 08:27:06 +0000 (UTC)
From:      Eitan Adler <eadler@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject:   svn commit: r330921 - stable/11/sys/dev/vt/hw/vga
Message-ID:  <201803140827.w2E8R6jq093161@repo.freebsd.org>
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Author: eadler
Date: Wed Mar 14 08:27:05 2018
New Revision: 330921
URL: https://svnweb.freebsd.org/changeset/base/330921

Log:
  MFC r330834:
  
  vt_vga: check if VGA is available from ACPI FADT table
  
  On x86 the IA-PC Boot Flags in the FADT can signal whether VGA is
  available or not.

Modified:
  stable/11/sys/dev/vt/hw/vga/vt_vga.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/vt/hw/vga/vt_vga.c
==============================================================================
--- stable/11/sys/dev/vt/hw/vga/vt_vga.c	Wed Mar 14 08:15:26 2018	(r330920)
+++ stable/11/sys/dev/vt/hw/vga/vt_vga.c	Wed Mar 14 08:27:05 2018	(r330921)
@@ -30,6 +30,8 @@
  * SUCH DAMAGE.
  */
 
+#include "opt_acpi.h"
+
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
@@ -46,6 +48,10 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/bus.h>
 
+#if ((defined(__amd64__) || defined(__i386__)) && defined(DEV_ACPI))
+#include <contrib/dev/acpica/include/acpi.h>
+#endif
+
 struct vga_softc {
 	bus_space_tag_t		 vga_fb_tag;
 	bus_space_handle_t	 vga_fb_handle;
@@ -1196,11 +1202,39 @@ vga_initialize(struct vt_device *vd, int textmode)
 	return (0);
 }
 
+static bool
+vga_acpi_disabled(void)
+{
+#if ((defined(__amd64__) || defined(__i386__)) && defined(DEV_ACPI))
+	ACPI_TABLE_FADT *fadt;
+	vm_paddr_t physaddr;
+	uint16_t flags;
+
+	physaddr = acpi_find_table(ACPI_SIG_FADT);
+	if (physaddr == 0)
+		return (false);
+
+	fadt = acpi_map_table(physaddr, ACPI_SIG_FADT);
+	if (fadt == NULL) {
+		printf("vt_vga: unable to map FADT ACPI table\n");
+		return (false);
+	}
+
+	flags = fadt->BootFlags;
+	acpi_unmap_table(fadt);
+
+	if (flags & ACPI_FADT_NO_VGA)
+		return (true);
+#endif
+
+	return (false);
+}
+
 static int
 vga_probe(struct vt_device *vd)
 {
 
-	return (CN_INTERNAL);
+	return (vga_acpi_disabled() ? CN_DEAD : CN_INTERNAL);
 }
 
 static int

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