From: jsg <jsg@openbsd.org>
Date: Mon, 24 Jul 2023 14:02:36 +0000 (+0000)
Subject: after the boot block changes on i386, sthen noticed a dmesg change
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=860234e8477849e80921da12a4ca79bb3e7e7d88;p=openbsd

after the boot block changes on i386, sthen noticed a dmesg change
-pci0 at mainbus0 bus 0: configuration mode 1 (bios)
+pci0 at mainbus0 bus 0: configuration mode 1 (no bios)

deraadt then spent many hours narrowing down the problem to the inline
assembly in pciprobe().

It tried to save the carry flag result of pci bios present.  But did so
after a shift which sets the carry flag.  Ask for CF in the output and
avoid the shift.

ok deraadt@ kettenis@
---

diff --git a/sys/arch/i386/stand/libsa/pciprobe.c b/sys/arch/i386/stand/libsa/pciprobe.c
index 9854aa4cb5b..46c0117aa64 100644
--- a/sys/arch/i386/stand/libsa/pciprobe.c
+++ b/sys/arch/i386/stand/libsa/pciprobe.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pciprobe.c,v 1.10 2014/03/29 18:09:29 guenther Exp $	*/
+/*	$OpenBSD: pciprobe.c,v 1.11 2023/07/24 14:02:36 jsg Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -39,12 +39,12 @@ pciprobe(void)
 {
 	bios_pciinfo_t bpi;
 	u_int32_t hw_chars, rev, rc, sig;
-	u_int32_t entry32;
+	u_int32_t entry32, lastbus;
 
 	/* PCI BIOS v2.0c+ - Installation Check */
-	__asm volatile(DOINT(0x1A) "; shll $8,%2; setc %b2"
-		: "=a" (hw_chars), "=b" (rev), "=c" (rc),
-		  "=d" (sig), "=D" (entry32)
+	__asm volatile(DOINT(0x1A)
+		: "=a" (hw_chars), "=b" (rev), "=c" (lastbus),
+		  "=d" (sig), "=D" (entry32), "=@ccc" (rc)
 		: "0" (0xB101), "4" (0x0)
 		: "cc");
 
@@ -62,7 +62,7 @@ pciprobe(void)
 	bpi.pci_chars = hw_chars & 0xFFFF;
 	bpi.pci_rev = rev & 0xFFFF;
 	bpi.pci_entry32 = entry32;
-	bpi.pci_lastbus = (rc>>8) & 0xFF;
+	bpi.pci_lastbus = lastbus & 0xFF;
 
 	addbootarg(BOOTARG_PCIINFO, sizeof(bios_pciinfo_t), &bpi);
 }