[src/trunk]: src/sys/arch/x86 x86: Fix interaction between consinit, device_p...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/5f26ade676d0
branches:  trunk
changeset: 369877:5f26ade676d0
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Sep 05 14:18:51 2022 +0000

description:
x86: Fix interaction between consinit, device_pci_register, and drm.

Leave an essay on what's going on here in both places with
cross-references.

PR kern/56996

diffstat:

 sys/arch/x86/pci/pci_machdep.c |  35 +++++++++++++++++++++++++----------
 sys/arch/x86/x86/consinit.c    |  13 +++++++++++--
 2 files changed, 36 insertions(+), 12 deletions(-)

diffs (90 lines):

diff -r b4b8e5fa1ef9 -r 5f26ade676d0 sys/arch/x86/pci/pci_machdep.c
--- a/sys/arch/x86/pci/pci_machdep.c    Mon Sep 05 14:14:42 2022 +0000
+++ b/sys/arch/x86/pci/pci_machdep.c    Mon Sep 05 14:18:51 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pci_machdep.c,v 1.91 2022/05/24 14:00:23 bouyer Exp $  */
+/*     $NetBSD: pci_machdep.c,v 1.92 2022/09/05 14:18:51 riastradh Exp $       */
 
 /*-
  * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@@ -73,7 +73,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pci_machdep.c,v 1.91 2022/05/24 14:00:23 bouyer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pci_machdep.c,v 1.92 2022/09/05 14:18:51 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/param.h>
@@ -1228,14 +1228,29 @@
                         */
                        populate_fbinfo(dev, dict);
 
-#if 1 && NWSDISPLAY > 0 && NGENFB > 0
-                       /* XXX */
-                       if (device_is_a(dev, "genfb")) {
-                               prop_dictionary_set_bool(dict, "is_console",
-                                   genfb_is_console());
-                       } else
-#endif
-                       prop_dictionary_set_bool(dict, "is_console", true);
+                       /*
+                        * If the bootloader requested console=pc and
+                        * specified a framebuffer, and if
+                        * x86_genfb_cnattach succeeded in setting it
+                        * up during consinit, then consinit will call
+                        * genfb_cnattach which makes genfb_is_console
+                        * return true.  In this case, if it's the
+                        * first genfb we've seen, we will instruct the
+                        * genfb driver via the is_console property
+                        * that it has been selected as the console.
+                        *
+                        * If not all of that happened, then consinit
+                        * can't have selected a genfb console, so this
+                        * device is definitely not the console.
+                        *
+                        * XXX What happens if there's more than one
+                        * PCI display device, and the bootloader picks
+                        * the second one's framebuffer as the console
+                        * framebuffer address?  Tough...but this has
+                        * probably never worked.
+                        */
+                       prop_dictionary_set_bool(dict, "is_console",
+                           genfb_is_console());
 
                        prop_dictionary_set_bool(dict, "clear-screen", false);
 #if NWSDISPLAY > 0 && NGENFB > 0
diff -r b4b8e5fa1ef9 -r 5f26ade676d0 sys/arch/x86/x86/consinit.c
--- a/sys/arch/x86/x86/consinit.c       Mon Sep 05 14:14:42 2022 +0000
+++ b/sys/arch/x86/x86/consinit.c       Mon Sep 05 14:18:51 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: consinit.c,v 1.34 2021/10/07 12:52:27 msaitoh Exp $    */
+/*     $NetBSD: consinit.c,v 1.35 2022/09/05 14:18:51 riastradh Exp $  */
 
 /*
  * Copyright (c) 1998
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: consinit.c,v 1.34 2021/10/07 12:52:27 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: consinit.c,v 1.35 2022/09/05 14:18:51 riastradh Exp $");
 
 #include "opt_kgdb.h"
 #include "opt_puc.h"
@@ -195,6 +195,15 @@
                int error;
 #if (NGENFB > 0)
                if (fbinfo && fbinfo->physaddr > 0) {
+                       /*
+                        * If we have a framebuffer address, and
+                        * x86_genfb_cnattach can map it, then
+                        * genfb_cnattach causes genfb_is_console to
+                        * later return true.  device_pci_register will
+                        * use this to set up the device properties for
+                        * a PCI display-class device to notify it that
+                        * it has been selected as the console.
+                        */
                        if (x86_genfb_cnattach() == -1) {
                                initted = 0;    /* defer */
                                return;