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From: Neel Natu <neel@FreeBSD.org>
Date: Tue, 27 Aug 2013 16:50:48 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r254965 - head/usr.sbin/bhyve
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Author: neel
Date: Tue Aug 27 16:50:48 2013
New Revision: 254965
URL: http://svnweb.freebsd.org/changeset/base/254965

Log:
  Allow single byte reads of the emulated MSI-X tables. This is not required
  by the PCI specification but needed to dump MMIO space from "ddb" in the
  guest.

Modified:
  head/usr.sbin/bhyve/pci_emul.c

Modified: head/usr.sbin/bhyve/pci_emul.c
==============================================================================
--- head/usr.sbin/bhyve/pci_emul.c	Tue Aug 27 16:49:20 2013	(r254964)
+++ head/usr.sbin/bhyve/pci_emul.c	Tue Aug 27 16:50:48 2013	(r254965)
@@ -245,8 +245,12 @@ pci_emul_msix_tread(struct pci_devinst *
 	int tab_index;
 	uint64_t retval = ~0;
 
-	/* support only 4 or 8 byte reads */
-	if (size != 4 && size != 8)
+	/*
+	 * The PCI standard only allows 4 and 8 byte accesses to the MSI-X
+	 * table but we also allow 1 byte access to accomodate reads from
+	 * ddb.
+	 */
+	if (size != 1 && size != 4 && size != 8)
 		return (retval);
 
 	msix_entry_offset = offset % MSIX_TABLE_ENTRY_SIZE;
@@ -263,7 +267,9 @@ pci_emul_msix_tread(struct pci_devinst *
 		dest = (char *)(pi->pi_msix.table + tab_index);
 		dest += msix_entry_offset;
 
-		if (size == 4)
+		if (size == 1)
+			retval = *((uint8_t *)dest);
+		else if (size == 4)
 			retval = *((uint32_t *)dest);
 		else
 			retval = *((uint64_t *)dest);