From 0a6624b26dd8006a75725e5379431abf1c5b0f09 Mon Sep 17 00:00:00 2001
From: Serge Schneider <serge@raspberrypi.org>
Date: Fri, 24 Jan 2020 12:48:57 +0000
Subject: [PATCH] Update ROOT_MARGIN

---
 Dockerfile             | 2 +-
 README.md              | 2 +-
 depends                | 1 +
 export-image/prerun.sh | 2 +-
 4 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 706a5fb..35f483a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get -y update && \
     apt-get -y install \
         git vim parted \
         quilt coreutils qemu-user-static debootstrap zerofree zip dosfstools \
-        bsdtar libcap2-bin rsync grep udev xz-utils curl xxd file kmod\
+        bsdtar libcap2-bin rsync grep udev xz-utils curl xxd file kmod bc\
     && rm -rf /var/lib/apt/lists/*
 
 COPY . /pi-gen/
diff --git a/README.md b/README.md
index bf681fa..ec4f65c 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ To install the required dependencies for pi-gen you should run:
 
 ```bash
 apt-get install coreutils quilt parted qemu-user-static debootstrap zerofree zip \
-dosfstools bsdtar libcap2-bin grep rsync xz-utils file git curl
+dosfstools bsdtar libcap2-bin grep rsync xz-utils file git curl bc
 ```
 
 The file `depends` contains a list of tools needed.  The format of this
diff --git a/depends b/depends
index 6238eb1..a86bc82 100644
--- a/depends
+++ b/depends
@@ -16,3 +16,4 @@ xxd
 file
 git
 lsmod:kmod
+bc
diff --git a/export-image/prerun.sh b/export-image/prerun.sh
index cecde32..8bbc566 100755
--- a/export-image/prerun.sh
+++ b/export-image/prerun.sh
@@ -18,7 +18,7 @@ ALIGN="$((4 * 1024 * 1024))"
 # some overhead (since actual space usage is usually rounded up to the
 # filesystem block size) and gives some free space on the resulting
 # image.
-ROOT_MARGIN=$((800*1024*1024))
+ROOT_MARGIN="$(echo "($ROOT_SIZE * 0.2 + 200 * 1024 * 1024) / 1" | bc)"
 
 BOOT_PART_START=$((ALIGN))
 BOOT_PART_SIZE=$(((BOOT_SIZE + ALIGN - 1) / ALIGN * ALIGN))