support machines without PCI

Instead of panicing when a PCI bus isn't found, continue booting
without PCI nor ACPI initialization.

Signed-off-by: Sergio Lopez <slp@redhat.com>

3 files changed, 12 insertions, 6 deletions

diff --git a/hwsetup.c b/hwsetup.c
index 6eae3fa..250213e 100644
--- a/hwsetup.c
+++ b/hwsetup.c
@@ -94,7 +94,7 @@ void setup_pam(int bdf, int pambase)
 	pci_config_writeb(bdf, pambase, 0x30);
 }
 
-void setup_hw(void)
+bool setup_hw(void)
 {
 	const int bdf = 0;
 	const uint8_t *bios_start = (void *)((uintptr_t)&stext + 0xfff00000);
@@ -112,8 +112,9 @@ void setup_hw(void)
 		setup_ich9();
 		setup_ich9_pm();
 		pambase = Q35_HOST_BRIDGE_PAM0;
-	} else
-		panic();
+	} else {
+		return false;
+	}
 
 	// Make ram from 0xc0000-0xf0000 read-write
 	rom_check_value = rom_check;
@@ -126,6 +127,8 @@ void setup_hw(void)
 	memcpy(&sinit, init_start, &einit - &sinit);
 
 	setup_pic();
+
+	return true;
 }
 
 #define Q35_HOST_BRIDGE_PCIEXBAREN      1
diff --git a/include/bios.h b/include/bios.h
index 3e4cdee..1469cb6 100644
--- a/include/bios.h
+++ b/include/bios.h
@@ -64,7 +64,7 @@ extern void bios32_entry(void);
 extern uint32_t pic_base(void);
 
 extern void setup_pci(void);
-extern void setup_hw(void);
+extern bool setup_hw(void);
 extern bool setup_mmconfig(void);
 extern void extract_acpi(void);
 extern void boot_from_fwcfg(void);
diff --git a/main.c b/main.c
index f66693b..b20a7de 100644
--- a/main.c
+++ b/main.c
@@ -79,10 +79,11 @@ static void extract_e820(void)
 
 int __attribute__ ((section (".text.startup"))) main(void)
 {
+	bool have_pci;
 #ifdef BENCHMARK_HACK
 	outb(FW_EXIT_PORT, FW_START);
 #endif
-	setup_hw();
+	have_pci = setup_hw();
 
 	// Only the 16-bit trampoline for vmlinuz and the 16-bit interrupt
 	// handlers need to run from the F-segment, but keep things simple
@@ -90,7 +91,9 @@ int __attribute__ ((section (".text.startup"))) main(void)
 	asm("ljmp $0x8, $1f; 1:");
 
 	have_mmconfig = setup_mmconfig();
-	setup_pci();
+	if (have_pci) {
+		setup_pci();
+	}
 	setup_idt();
 	fw_cfg_setup();
 	extract_acpi();