From 456b8c4d2424e52f7861e14d667ba7c26ca1cce3 Mon Sep 17 00:00:00 2001
From: Joel Granados Moreno <jgranado@redhat.com>
Date: Fri, 5 Jun 2009 14:14:08 +0200
Subject: [PATCH] Preserve first 446 bytes of the pmbr in gpt.
* libparted/label/gpt.c (_write_pmbr) : Make sure we read the first 446
bytes of the device when we are creating the pmbr.
---
libparted/labels/gpt.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/libparted/labels/gpt.c b/libparted/labels/gpt.c
index 73bdbb2..f1c4f69 100644
--- a/libparted/labels/gpt.c
+++ b/libparted/labels/gpt.c
@@ -982,7 +982,18 @@ _write_pmbr (PedDevice * dev)
{
LegacyMBR_t pmbr;
- memset(&pmbr, 0, sizeof(pmbr));
+ /* The UEFI spec is not clear about what to do with the following
+ * elements of the Protective MBR (pmbr): BootCode (0-440B),
+ * UniqueMBRSignature (440B-444B) and Unknown (444B-446B).
+ * With this in mind, we try not to modify these elements.
+ */
+ if(ped_device_read(dev, &pmbr, 0, GPT_PMBR_SECTORS) < GPT_PMBR_SECTORS)
+ memset(&pmbr, 0, sizeof(pmbr));
+
+ /* Make sure we zero out all the legacy partitions.
+ * There are 4 PartitionRecords. */
+ memset(&(pmbr.PartitionRecord), 0, sizeof(PartitionRecord_t) * 4);
+
pmbr.Signature = PED_CPU_TO_LE16(MSDOS_MBR_SIGNATURE);
pmbr.PartitionRecord[0].OSType = EFI_PMBR_OSTYPE_EFI;
pmbr.PartitionRecord[0].StartSector = 1;
--
1.6.0.6