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Date: Mon, 12 Jan 2015 10:28:02 +0100
From: Peter Lieven <pl@kamp.de>
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Subject: [Qemu-devel] Missing Diag/Debug Registers in lsi53c895a emulation
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To: Paolo Bonzini <pbonzini@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

Hi,

while trying to run an ASA1000V appliance I found that registers 0x09 and 0x3c-3f are read during boot up. Which
currently results in an exit(1). The appliance uses an quite ancient 2.6.29.6 Linux kernel.
These registers are mainly for diag and debug purposes so I came up with the following patch. The system works
with the following patch, but I wonder if this is a correct workaround:

diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
index ec92048..bce1135 100644
--- a/hw/scsi/lsi53c895a.c
+++ b/hw/scsi/lsi53c895a.c
@@ -1513,6 +1513,8 @@ static uint8_t lsi_reg_readb(LSIState *s, int offset)
          return 0x7f;
      case 0x08: /* Revision ID */
          return 0x00;
+    case 0x09: /* SOCL */
+        return 0x00;
      case 0xa: /* SSID */
          return s->ssid;
      case 0xb: /* SBCL */
@@ -1577,6 +1579,11 @@ static uint8_t lsi_reg_readb(LSIState *s, int offset)
          return s->sbr;
      case 0x3b: /* DCNTL */
          return s->dcntl;
+    case 0x3c: /* ADDER Output (Debug purpose only) */
+    case 0x3d:
+    case 0x3e:
+    case 0x3f:
+        return 0x00;
      case 0x40: /* SIEN0 */
          return s->sien0;
      case 0x41: /* SIEN1 */

Peter