diff -rupN grub2-2.02~beta2/debian/build-efi-images grub2-2.02~beta2-partxloop/debian/build-efi-images
--- grub2-2.02~beta2/debian/build-efi-images	2018-01-24 16:21:35.000000000 -0500
+++ grub2-2.02~beta2-partxloop/debian/build-efi-images	2019-09-16 10:59:39.356901056 -0400
@@ -30,6 +30,9 @@ outdir="$3"
 platform="$4"
 efi_name="$5"
 
+# mkfs.msdos may not be on the default PATH.
+export PATH="$PATH:/sbin:/usr/sbin"
+
 workdir=
 
 cleanup () {
diff -rupN grub2-2.02~beta2/debian/changelog grub2-2.02~beta2-partxloop/debian/changelog
--- grub2-2.02~beta2/debian/changelog	2019-08-08 19:36:44.610112109 -0400
+++ grub2-2.02~beta2-partxloop/debian/changelog	2019-09-16 11:05:37.231291334 -0400
@@ -1,3 +1,13 @@
+grub2 (2.02~beta2-36ubuntu3.23) xenial; urgency=medium
+
+  * debian/patches/Support-partitioned-partx-loop-devices.patch:
+    Cherry-pick upstream patch to install to partitioned loop devices (LP: #1824245)
+  * debian/control: Add missing 'dosfstools' Build-Depends to make efi images
+  * debian/build-efi-images: Ensure that build-efi-images has a suitable PATH
+    for running mkfs.msdos (backported from Debian to close #852001)
+
+ -- Neal Gompa <ngompa@datto.com>  Mon, 16 Sep 2019 11:05:08 -0400
+
 grub2 (2.02~beta2-36ubuntu3.22) xenial; urgency=medium
 
   * debian/patches/skip_text_gfxpayload_where_not_supported.patch: Skip the
diff -rupN grub2-2.02~beta2/debian/control grub2-2.02~beta2-partxloop/debian/control
--- grub2-2.02~beta2/debian/control	2018-01-24 16:21:35.000000000 -0500
+++ grub2-2.02~beta2-partxloop/debian/control	2019-04-25 10:17:14.067543172 -0400
@@ -8,6 +8,7 @@ Build-Depends: debhelper (>= 7.4.2~),
  patchutils,
  dh-autoreconf,
  automake,
+ dosfstools,
  python,
  flex,
  bison,
diff -rupN grub2-2.02~beta2/debian/patches/series grub2-2.02~beta2-partxloop/debian/patches/series
--- grub2-2.02~beta2/debian/patches/series	2019-08-08 19:39:18.440004523 -0400
+++ grub2-2.02~beta2-partxloop/debian/patches/series	2019-08-08 19:39:57.322724308 -0400
@@ -135,3 +135,4 @@ linuxefi_fix_relocate_coff.patch
 linuxefi_truncate_overlong_relocs.patch
 squash4-fix-fragments-and-sparse-files.patch
 skip_text_gfxpayload_where_not_supported.patch
+Support-partitioned-partx-loop-devices.patch
diff -rupN grub2-2.02~beta2/debian/patches/Support-partitioned-partx-loop-devices.patch grub2-2.02~beta2-partxloop/debian/patches/Support-partitioned-partx-loop-devices.patch
--- grub2-2.02~beta2/debian/patches/Support-partitioned-partx-loop-devices.patch	1969-12-31 19:00:00.000000000 -0500
+++ grub2-2.02~beta2-partxloop/debian/patches/Support-partitioned-partx-loop-devices.patch	2019-04-10 17:27:47.765266675 -0400
@@ -0,0 +1,45 @@
+From 21026cb20c81fba1d639c00779413aa71bf24e75 Mon Sep 17 00:00:00 2001
+From: Neal Gompa <ngompa@datto.com>
+Date: Wed, 10 Apr 2019 17:25:31 -0400
+Subject: [PATCH] Backport support for partitioned partx loop devices in
+ grub-install
+
+Cherry-picked from 35f2d96c0d68772c831952b2ee4eba6519d6ea1b
+
+From: Mike Gilbert <floppym@gentoo.org>
+Date: Sun, 26 Jan 2014 02:56:04 +0100
+Subject: grub-install: support for partitioned partx loop devices.
+
+* grub-core/osdep/linux/getroot.c (grub_util_part_to_disk): Detect
+/dev/loopX as being the parent of /dev/loopXpY.
+---
+ grub-core/osdep/linux/getroot.c | 13 +++++++++++++
+ 1 file changed, 13 insertions(+)
+
+diff --git a/grub-core/osdep/linux/getroot.c b/grub-core/osdep/linux/getroot.c
+index f97f3a6..ad47d45 100644
+--- a/grub-core/osdep/linux/getroot.c
++++ b/grub-core/osdep/linux/getroot.c
+@@ -910,6 +910,19 @@ grub_util_part_to_disk (const char *os_dev, struct stat *st,
+ 
+ 	  return path;
+ 	}
++
++      /* If this is a loop device */
++      if ((strncmp ("loop", p, 4) == 0) && p[4] >= '0' && p[4] <= '9')
++	{
++	  char *pp = p + 4;
++	  while (*pp >= '0' && *pp <= '9')
++	    pp++;
++	  if (*pp == 'p')
++	    *is_part = 1;
++	  /* /dev/loop[0-9]+p[0-9]* */
++	  *pp = '\0';
++	  return path;
++	}
+     }
+ 
+   return path;
+-- 
+2.20.1
+