[Qemu-devel] sparc esp dma endianness [patch-rfc]

[Artyom Tarasenko]

Trying to find out what could be the mysterious scsi commands 60, 80,
c0 and e0, I found out that OBP during dma exchange has problems with
endianness.
OBP sends commands like this:
12 20 00 00 05 00 or this 12 80 00 00 05 00, but esp.c expects
that the second byte is the command and the first one is the target.

The following patch solves the problem, but breaks OpenBIOS. The
question is where do we have wrong endianness? It's not necessarily
esp, it may be something on the way like dma or mmu. Any ideas?

diff --git a/hw/esp.c b/hw/esp.c
index aad547e..aceee48 100644
--- a/hw/esp.c
+++ b/hw/esp.c
@@ -169,11 +169,17 @@ static uint32_t get_cmd(ESPState *s, uint8_t *buf)
 {
     uint32_t dmalen;
     int target;
-
-    target = s->wregs[ESP_WBUSID] & BUSID_DID;
-    if (s->dma) {
-        dmalen = s->rregs[ESP_TCLO] | (s->rregs[ESP_TCMID] << 8);
-        s->dma_memory_read(s->dma_opaque, buf, dmalen);
+    uint8_t tmp,i;
+
+    target = s->wregs[ESP_WBUSID] & BUSID_DID;
+     if (s->dma) {
+         dmalen = s->rregs[ESP_TCLO] | (s->rregs[ESP_TCMID] << 8);
+         s->dma_memory_read(s->dma_opaque, buf, dmalen);
+         for(i=0;i<dmalen;i+=2) {
+             tmp=buf[i];
+             buf[i]=buf[i+1];
+             buf[i+1]=tmp;
+         }
     } else {
         dmalen = s->ti_size;
         memcpy(buf, s->ti_buf, dmalen);

with the patch probing looks like this:

ok probe-scsi
Target 0
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 0   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 1   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 2   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 3   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 4   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 5   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 6   Disk
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 7   Disk
Target 2
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 0   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 1   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 2   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 3   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 4   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 5   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 6   Removable Read Only device
scsi-disk: Error: Inquiry (STANDARD) buffer size 5 is less than 36
(TODO: only 5 required)
  Unit 7   Removable Read Only device
ok

without patch it looks like this:

ok probe-scsi
Target 0
scsi-disk: Unsupported command length, command 60
scsi-disk: Unsupported command length, command 60
scsi-disk: Unsupported command length, command c0
scsi-disk: Unsupported command length, command c0
scsi-disk: Unsupported command length, command e0
scsi-disk: Unsupported command length, command e0
Target 2
scsi-disk: Unsupported command length, command 60
scsi-disk: Unsupported command length, command 60
scsi-disk: Unsupported command length, command c0
scsi-disk: Unsupported command length, command c0
scsi-disk: Unsupported command length, command e0
scsi-disk: Unsupported command length, command e0
ok