kern/amd64: boot: Disable the i8259 chip on boot

To avoid interrupt conflicts on some machines with the I/O APIC, disable
the legacy i8259 chip by default

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 42 insertions, 0 deletions

diff --git a/src/sys/arch/amd64/boot/boot_chip.c b/src/sys/arch/amd64/boot/boot_chip.c
index 80daf27..737309f 100644
--- a/src/sys/arch/amd64/boot/boot_chip.c
+++ b/src/sys/arch/amd64/boot/boot_chip.c
@@ -31,10 +31,12 @@
 #include <machine/uart.h>
 #include <machine/gdt.h>
 #include <machine/boot.h>
+#include <machine/i8259.h>
 
 void
 platform_boot(void)
 {
     gdt_load();
+    i8259_disable();
     uart_init();
 }
diff --git a/src/sys/arch/amd64/intel/i8259.c b/src/sys/arch/amd64/intel/i8259.c
new file mode 100644
index 0000000..127a3e1
--- /dev/null
+++ b/src/sys/arch/amd64/intel/i8259.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <machine/i8259.h>
+
+/*
+ * Disable the i8259
+ */
+void
+i8259_disable(void)
+{
+    outb(PIC1_DATA, 0xFF);
+    outb(PIC2_DATA, 0xFF);
+}