svn commit: r346969 - head/stand/i386/zfsboot

[Toomas Soome]

Author: tsoome
Date: Tue Apr 30 17:45:22 2019
New Revision: 346969
URL: https://svnweb.freebsd.org/changeset/base/346969

Log:
  zfsboot: to detect disk size, use GPT information first
  
  If we do have GPT on disk, read the disk size from it and do not
  call int13.
  
  Since int13 does report bogus informatiopn too often, rather trust the
  partition table. We are using the same strategy with loader.
  
  MFC after:	1 month

Modified:
  head/stand/i386/zfsboot/zfsboot.c

Modified: head/stand/i386/zfsboot/zfsboot.c
==============================================================================
--- head/stand/i386/zfsboot/zfsboot.c	Tue Apr 30 17:42:05 2019	(r346968)
+++ head/stand/i386/zfsboot/zfsboot.c	Tue Apr 30 17:45:22 2019	(r346969)
@@ -460,6 +460,33 @@ copy_dsk(struct zfsdsk *zdsk)
 }
 
 /*
+ * Get disk size from GPT.
+ */
+static uint64_t
+drvsize_gpt(struct dsk *dskp)
+{
+#ifdef GPT
+	struct gpt_hdr hdr;
+	char *sec;
+
+	sec = dmadat->secbuf;
+	if (drvread(dskp, sec, 1, 1))
+		return (0);
+
+	memcpy(&hdr, sec, sizeof(hdr));
+	if (memcmp(hdr.hdr_sig, GPT_HDR_SIG, sizeof(hdr.hdr_sig)) != 0 ||
+	    hdr.hdr_lba_self != 1 || hdr.hdr_revision < 0x00010000 ||
+	    hdr.hdr_entsz < sizeof(struct gpt_ent) ||
+	    DEV_BSIZE % hdr.hdr_entsz != 0) {
+		return (0);
+	}
+	return (hdr.hdr_lba_alt + 1);
+#else
+	return (0);
+#endif
+}
+
+/*
  * Get disk size from eax=0x800 and 0x4800. We need to probe both
  * because 0x4800 may not be available and we would like to get more
  * or less correct disk size - if it is possible at all.
@@ -474,6 +501,11 @@ drvsize_ext(struct zfsdsk *zdsk)
 	int cyl, hds, sec;
 
 	dskp = &zdsk->dsk;
+
+	/* Try to read disk size from GPT */
+	size = drvsize_gpt(dskp);
+	if (size != 0)
+		return (size);
 
 	v86.ctl = V86_FLAGS;
 	v86.addr = 0x13;