First cut at just unpacking the XiLinx tarball.

.dockerignore

@@ -1,2 +1,3 @@
+Dockerfile.later
 Makefile
 README.md

Dockerfile

@@ -1,25 +1,11 @@
 FROM debian:jessie
 
-RUN echo 'deb http://deb.debian.org/debian jessie-backports main' > /etc/apt/sources.list.d/backports.list
+# OK, let's start with the horrible XiLinx stuff because that's least
+# likely to change except when we're updating the base Docker image.
 
-# An assortment of normal Debian packages.  Might want to move this to
-# after the horrible XiLinx stuff so we don't have to redo that very often.
+# In theory, using ADD in this form will cause docker to unpack the
+# tarball directly into the filesystem, thus saving us an otherwise
+# useless 6GB copy operation, which seems worthwhile.
 
-RUN apt-get update \
-	&& \
-    apt-get install -y \
-	    avr-libc \
-	    binutils-avr \
-	    gcc-arm-none-eabi \
-	    gcc-avr \
-	    git \
-	    python-crypto \
-	    python-serial \
-	    python-yaml \
-	    reprepro \
-	    ubuntu-archive-keyring \
-	    ubuntu-dev-tools \
-	    pbuilder \
-	&& \
-    apt-get -t jessie-backports install -y \
-	    debootstrap distro-info-data
+RUN mkdir /xilinx-unpack
+ADD Xilinx_ISE_DS_Lin_14.7_1015_1.tar /xilinx-unpack/

Dockerfile.later

@@ -0,0 +1,25 @@
+FROM debian:jessie
+
+RUN echo 'deb http://deb.debian.org/debian jessie-backports main' > /etc/apt/sources.list.d/backports.list
+
+# An assortment of normal Debian packages.  Might want to move this to
+# after the horrible XiLinx stuff so we don't have to redo that very often.
+
+RUN apt-get update \
+	&& \
+    apt-get install -y \
+	    avr-libc \
+	    binutils-avr \
+	    gcc-arm-none-eabi \
+	    gcc-avr \
+	    git \
+	    python-crypto \
+	    python-serial \
+	    python-yaml \
+	    reprepro \
+	    ubuntu-archive-keyring \
+	    ubuntu-dev-tools \
+	    pbuilder \
+	&& \
+    apt-get -t jessie-backports install -y \
+	    debootstrap distro-info-data