svn commit: r245399 - projects/altix2/sys/geom/part

[Marcel Moolenaar]

Author: marcel
Date: Sun Jan 13 23:36:21 2013
New Revision: 245399
URL: http://svnweb.freebsd.org/changeset/base/245399

Log:
  Marking the PMBR as active may be needed for some BIOSes to boot from the
  disk, but also has some EFI implementations reject the GPT altogether.
  Make the behaviour controllable by a sysctll and have it default to 1
  on i386 and amd64 and 0 otherwise. This means that we mark the PMBR as
  active on i386 and amd64 by default, but remain compliant most of the
  time.

Modified:
  projects/altix2/sys/geom/part/g_part_gpt.c

Modified: projects/altix2/sys/geom/part/g_part_gpt.c
==============================================================================
--- projects/altix2/sys/geom/part/g_part_gpt.c	Sun Jan 13 23:00:40 2013	(r245398)
+++ projects/altix2/sys/geom/part/g_part_gpt.c	Sun Jan 13 23:36:21 2013	(r245399)
@@ -50,6 +50,20 @@ __FBSDID("$FreeBSD$");
 
 FEATURE(geom_part_gpt, "GEOM partitioning class for GPT partitions support");
 
+SYSCTL_DECL(_kern_geom_part);
+static SYSCTL_NODE(_kern_geom_part, OID_AUTO, gpt, CTLFLAG_RW, 0,
+    "gpart GPT controls");
+
+#if defined(__i386__) || defined(__amd64__)
+#define	PMBR_ACTIVE	1
+#else
+#define	PMBR_ACTIVE	0
+#endif
+
+static u_int gpt_mark_pmbr_active = PMBR_ACTIVE;
+SYSCTL_UINT(_kern_geom_part_gpt, OID_AUTO, mark_pmbr_active, CTLFLAG_RW,
+    &gpt_mark_pmbr_active, 0, "Mark the PMBR active on creation");
+
 CTASSERT(offsetof(struct gpt_hdr, padding) == 92);
 CTASSERT(sizeof(struct gpt_ent) == 128);
 
@@ -1040,7 +1054,8 @@ g_part_gpt_write(struct g_part_table *ba
 		gpt_write_mbr_entry(table->mbr, 0, 0xee, 1,
 		    MIN(pp->mediasize / pp->sectorsize - 1, UINT32_MAX));
 		/* Mark the PMBR active since some BIOS require it. */
-		table->mbr[DOSPARTOFF] = 0x80;
+		if (gpt_mark_pmbr_active)
+			table->mbr[DOSPARTOFF] = 0x80;
 	}
 	le16enc(table->mbr + DOSMAGICOFFSET, DOSMAGIC);