Merge casper:lp.1899308 into casper:main

[Steve Langasek]

[Dimitri John Ledkov (xnox)]

review: Approve (ship it)

diff --git a/debian/changelog b/debian/changelog
index 1bdd120..7aff181 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,16 @@
+casper (1.453) UNRELEASED; urgency=medium
+
+  * If creating a persistent partition, manually restore a 'bootable' flag
+    on any protective MBR, if present, to ensure compatibility with BIOS
+    implementations which require this.  This is slightly different from
+    the xorriso implementation, because we mark the iso9660 partition as
+    bootable instead of creating a separate empty partition, but anything
+    looking at the MBR should be fine and anything that's GPT-aware should
+    not care.  LP: #1899308
+  * Document the VCS for this package.
+
+ -- Steve Langasek <[e-mail]>  Thu, 15 Oct 2020 09:06:25 -0700
+
 casper (1.452) groovy; urgency=medium
 
   * casper: ask user for netmask, because we lack CIDR notation support
diff --git a/debian/control b/debian/control
index 03d15c9..3620980 100644
--- a/debian/control
+++ b/debian/control
@@ -4,6 +4,7 @@ Priority: optional
 Maintainer: Ubuntu Developers <[e-mail]>
 Build-Depends: debhelper (>= 7.0.50~), lsb-release, libplymouth-dev (>= 0.8.0~-13), pkg-config, dh-systemd
 Standards-Version: 3.9.3
+Vcs-Git: lp:casper
 
 Package: casper
 Architecture: any
diff --git a/scripts/casper-helpers b/scripts/casper-helpers
index 7479d98..bb019d5 100644
--- a/scripts/casper-helpers
+++ b/scripts/casper-helpers
@@ -298,6 +298,14 @@ find_or_create_persistent_partition () {
         return
     fi
     echo "start=$start" | sfdisk --no-reread -q $DEVICE -a || return
+    # If our partition table is GPT, we *may* have a protective MBR; ensure
+    # that after adding a new partition, if there is a protective MBR, we
+    # mark *a* partition bootable for compatibility (GRUB doesn't actually
+    # care which partition is marked bootable, but some BIOSes care that
+    # it exists).
+    if sfdisk -d $DEVICE | grep -q 'label: gpt'; then
+        sfdisk --no-reread -q $DEVICE -A 1 -X dos || true
+    fi
     for d in ${DEVICE}$newpartno ${DEVICE}p$newpartno ${DEVICE}-part$newpartno; do
         if [ -e $d ]; then
             mkfs.ext4 -q -L "$(root_persistence_label)" -F $d