shithub: riscv

Download patch

ref: a5764f8181d4e13f7e4b93c2565f0663b2fbc436
parent: d1604b5f9ce1d64919a8b8313e1db22ebd8d5213
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Sun Oct 18 19:39:07 EDT 2020 

pc, pc64: remove mystery "type" bits in pcicfgrw*raw() (fixes qemu, thanks mischief)

the access functions for pci config space in config mode #1
used to set bit 0 in the register offset if the access was
to a device on any bus different from 0.

it is completely unclear why this was done and i can't find
any documentation on this.

but for sure, this breaks all pci config spacess access to
pci devices behind a bridge on qemu. with -trace pci* it
was discovered that all config space register offsets on
devies behind pci brige where off by one.

on real hardware, setting bit 0 in the offset doesnt appear
to be an issue.

thanks mischief for reporting and providing a qemu demo
configuration to reproduce the problem.


--- a/sys/src/9/pc/pcipc.c
+++ b/sys/src/9/pc/pcipc.c
@@ -36,17 +36,13 @@
 static int
 pcicfgrw8raw(int tbdf, int rno, int data, int read)
 {
-	int o, type;
+	int o;
 
-	if(BUSBNO(tbdf))
-		type = 0x01;
-	else
-		type = 0x00;
 	switch(pcicfgmode){
 	case 1:
 		o = rno & 0x03;
 		rno &= ~0x03;
-		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno|type);
+		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno);
 		if(read)
 			data = inb(PciDATA+o);
 		else
@@ -72,17 +68,13 @@
 static int
 pcicfgrw16raw(int tbdf, int rno, int data, int read)
 {
-	int o, type;
+	int o;
 
-	if(BUSBNO(tbdf))
-		type = 0x01;
-	else
-		type = 0x00;
 	switch(pcicfgmode){
 	case 1:
 		o = rno & 0x02;
 		rno &= ~0x03;
-		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno|type);
+		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno);
 		if(read)
 			data = ins(PciDATA+o);
 		else
@@ -108,16 +100,10 @@
 static int
 pcicfgrw32raw(int tbdf, int rno, int data, int read)
 {
-	int type;
-
-	if(BUSBNO(tbdf))
-		type = 0x01;
-	else
-		type = 0x00;
 	switch(pcicfgmode){
 	case 1:
 		rno &= ~0x03;
-		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno|type);
+		outl(PciADDR, 0x80000000|BUSBDF(tbdf)|rno);
 		if(read)
 			data = inl(PciDATA);
 		else