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acpi, vga: say what the first real boot actually found

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"acpi: 0 PCI interrupts routed through _PRT" on an AMD board meant that
every PCIe bridge's devices are wired to the second I/O APIC, which is not
driven. It says so now, and that those devices need MSI.

"vga: framebuffer disagreement" on an NVIDIA card compared the GOP's
framebuffer against BAR0, a 16 MB register block big enough to pass for a
screen. The BAR that contains the framebuffer is preferred now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
This commit is contained in:
Nexoniarz 2026-10-22 23:47:17 +02:00
commit 416aa52b09
2 changed files with 20 additions and 4 deletions
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10
kernel/acpi/aml.c
View file

@ -284,7 +284,7 @@ void
acpi_pci_route(void)
{
uacpi_pci_routing_table *roottab;
int i, routed = 0;
int i, routed = 0, beyond = 0;
if (!ready)
return;
@ -316,8 +316,11 @@ acpi_pci_route(void)
if (gsi < 0)
continue;
if (gsi >= NIRQ_IOAPIC) {
// A second I/O APIC's input. Not reachable here; MSI still is.
// A second I/O APIC's input. Not reachable here; MSI still is. AMD
// boards wire every PCIe bridge's devices to the GNB's I/O APIC, so
// on those this is most of the machine.
d->irq = 0xFF;
beyond++;
continue;
}
if (gsi != d->irq)
@ -331,4 +334,7 @@ acpi_pci_route(void)
uacpi_free_pci_routing_table(roottab);
kinfo("acpi: %d PCI interrupt%s routed through _PRT\n", routed,
routed == 1 ? "" : "s");
if (beyond)
kinfo("acpi: %d more on a second I/O APIC, which is not driven; "
"those devices need MSI\n", beyond);
}

14
kernel/drivers/gpu/vga/vga_pci.c
View file

@ -32,11 +32,21 @@
// Display controllers commonly expose two apertures -- the framebuffer and a
// much smaller register block -- and which index they land on varies, so the
// choice is made by size rather than by position.
//
// Except that the one the loader's mode actually lives in wins outright. An
// NVIDIA card's BAR0 is a 16 MB register block, which is big enough to pass
// for an 800x600 framebuffer and is not one; the screen is in BAR1. Taking
// the first that fits reported a "disagreement" that was the driver's own.
static struct pci_bar *
framebuffer_bar(struct pci_dev *d)
{
uint64 need = vga_fb_size();
uint64 need = vga_fb_size(), vbe = vga_fb_phys();
for (int i = 0; i < 6; i++) {
struct pci_bar *b = &d->bar[i];
if (b->base && !b->is_io && vbe >= b->base && vbe < b->base + b->size)
return b;
}
for (int i = 0; i < 6; i++) {
struct pci_bar *b = &d->bar[i];
if (b->base == 0 || b->is_io)
@ -64,7 +74,7 @@ vga_pci_probe(struct pci_dev *d)
return 0; // still ours; nothing more to do
}
if (vbe != 0 && bar->base != vbe) {
if (vbe != 0 && (vbe < bar->base || vbe >= bar->base + bar->size)) {
// Trust VBE: it describes the mode that is actually programmed and being
// displayed, which is the thing vga.c is writing into. The BAR is the
// card's whole aperture and the mode may sit at an offset within it. Say