From 0a220a413f15bc79c5b4ea58df3c018c7395f6c6 Mon Sep 17 00:00:00 2001
From: Liav A <liavalb@gmail.com>
Date: Fri, 2 Sep 2022 10:02:16 +0300
Subject: [PATCH] Kernel/PCI: Don't use x86 initialization methods in non-x86
 builds

Using the IO address space is only relevant for x86 machines, so let's
not compile instructions to access the PCI configuration space when we
don't target x86 platforms.
---
 Kernel/Bus/PCI/Initializer.cpp | 6 ++++++
 Kernel/CommandLine.cpp         | 2 ++
 Kernel/CommandLine.h           | 2 ++
 3 files changed, 10 insertions(+)

diff --git a/Kernel/Bus/PCI/Initializer.cpp b/Kernel/Bus/PCI/Initializer.cpp
index a6a9162368..2ca868014c 100644
--- a/Kernel/Bus/PCI/Initializer.cpp
+++ b/Kernel/Bus/PCI/Initializer.cpp
@@ -23,6 +23,7 @@ static bool test_pci_io();
 
 UNMAP_AFTER_INIT static PCIAccessLevel detect_optimal_access_type()
 {
+#if ARCH(I386) || ARCH(X86_64)
     auto boot_determined = kernel_command_line().pci_access_level();
     if (!ACPI::is_enabled() || !ACPI::Parser::the()->find_table("MCFG"sv).has_value())
         return PCIAccessLevel::IOAddressing;
@@ -32,6 +33,7 @@ UNMAP_AFTER_INIT static PCIAccessLevel detect_optimal_access_type()
 
     if (!g_pci_access_io_probe_failed)
         return PCIAccessLevel::IOAddressing;
+#endif
 
     PANIC("No PCI bus access method detected!");
 }
@@ -44,17 +46,21 @@ UNMAP_AFTER_INIT void initialize()
         return;
     switch (detect_optimal_access_type()) {
     case PCIAccessLevel::MemoryAddressing: {
+        // FIXME: There are other arch-specific methods to find the memory range
+        // for accessing the PCI configuration space.
         auto mcfg = ACPI::Parser::the()->find_table("MCFG"sv);
         VERIFY(mcfg.has_value());
         auto success = Access::initialize_for_multiple_pci_domains(mcfg.value());
         VERIFY(success);
         break;
     }
+#if ARCH(I386) || ARCH(X86_64)
     case PCIAccessLevel::IOAddressing: {
         auto success = Access::initialize_for_one_pci_domain();
         VERIFY(success);
         break;
     }
+#endif
     default:
         VERIFY_NOT_REACHED();
     }
diff --git a/Kernel/CommandLine.cpp b/Kernel/CommandLine.cpp
index b50f776a7e..ad9349f68d 100644
--- a/Kernel/CommandLine.cpp
+++ b/Kernel/CommandLine.cpp
@@ -149,8 +149,10 @@ UNMAP_AFTER_INIT PCIAccessLevel CommandLine::pci_access_level() const
     auto value = lookup("pci"sv).value_or("ecam"sv);
     if (value == "ecam"sv)
         return PCIAccessLevel::MemoryAddressing;
+#if ARCH(I386) || ARCH(X86_64)
     if (value == "io"sv)
         return PCIAccessLevel::IOAddressing;
+#endif
     if (value == "none"sv)
         return PCIAccessLevel::None;
     PANIC("Unknown PCI ECAM setting: {}", value);
diff --git a/Kernel/CommandLine.h b/Kernel/CommandLine.h
index 618f031088..28a48ac6e0 100644
--- a/Kernel/CommandLine.h
+++ b/Kernel/CommandLine.h
@@ -32,7 +32,9 @@ enum class AcpiFeatureLevel {
 
 enum class PCIAccessLevel {
     None,
+#if ARCH(I386) || ARCH(X86_64)
     IOAddressing,
+#endif
     MemoryAddressing,
 };