From a2f45232345c4e111651e3f809a3da8fd95f05bf Mon Sep 17 00:00:00 2001
From: Stefano Stabellini
Date: Fri, 16 Apr 2021 12:40:36 -0700
Subject: Generate xl config files to create DomUs from Dom0

disk_image generates xl config files to start DomUs from Dom0. The files
are added to dom0 rootfs partition under /etc/xen for your convenience.

They refer to kernels and ramdisks stored on the first partition. It is
recommended to mount the first partition under /boot in Dom0 to use
them.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Brian Woods <brian.woods@xilinx.com>
---
 README.md          |   9 +++++
 scripts/disk_image | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)

diff --git a/README.md b/README.md
index 4adb9dc..14cfc8e 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,10 @@ Where:
 
 - DOMU_KERNEL[number] specifies the DomU kernel to use.
 
+- DOMU_CMD[number] specifies the command line arguments for Dom0's Linux
+  kernel.  If "root=" isn't set, imagebuilder will try to determine it.
+  If not set at all, the default one is used.
+
 - DOMU_RAMDISK[number] specifies the DomU ramdisk to use.
 
 - DOMU_PASSTHROUGH_DTB[number] specifies the device assignment
@@ -145,3 +149,8 @@ Where:\
    "scsi" are shorthands for "tftpb", "load mmc 0:1" and
    "load scsi 0:1", but actually any arbitrary command can be used, for
    instance -t "fatload" is valid.
+
+
+disk_image also generates on the fly a xl config file for each domU and
+adds them to the dom0 rootfs partition under /etc/xen. It makes it
+easier to start those domUs from dom0.
diff --git a/scripts/disk_image b/scripts/disk_image
index eeb888f..8bc1312 100755
--- a/scripts/disk_image
+++ b/scripts/disk_image
@@ -17,6 +17,92 @@ function check_depends()
     done
 }
 
+function add_rootfs()
+{
+    local dev=${LOAD_CMD%:*}
+    dev=${dev##* }
+    local par=${LOAD_CMD#*:}
+    local j=$1
+
+    if [ -z "$dev" ] || [ -z "$par" ]
+    then
+        echo "Could not parse device and partition."
+        exit 1
+    fi
+
+    par=$(( $par + $j ))
+
+    if [[ $LOAD_CMD =~ mmc ]]
+    then
+        retval="/dev/mmcblk${dev}p${par}"
+    elif [[ $LOAD_CMD =~ scsi ]]
+    then
+        # converts number to a scsi device character
+        dev=$((dev + 97))
+        dev=$(printf %x $dev)
+        dev=$(printf "\x$dev")
+
+        retval="/dev/sd${dev}${par}"
+    else
+        echo "Only mmc and scsi are supported for automatically setting the root partition."
+        echo "Manually set DOM0_CMD with the root device in the config file to bypass this."
+        exit 1
+    fi
+}
+
+function generate_domU_configs()
+{
+    local i=0
+    local j=$1
+    # $j + 1 - 1 as it is starting from 0
+    local n=$1
+    local dest
+
+    mount -t ext4 /dev/mapper/diskimage$j $DESTDIR/part/disk$j
+    mkdir -p $DESTDIR/part/disk$j/etc/xen
+    add_rootfs 0
+    first_part=$retval
+
+    while test $i -lt $NUM_DOMUS
+    do
+        dest="$DESTDIR/part/disk$j/etc/xen/domU$i.cfg"
+        echo "name=\"domU$i\"" >> $dest
+        echo "memory=${DOMU_MEM[$i]}" >> $dest
+        echo "vcpus=${DOMU_VCPUS[$i]}" >> $dest
+        echo "# mount $first_part /boot" >> $dest
+        echo "kernel=\"/boot/${DOMU_KERNEL[$i]}\"" >> $dest
+        if test "${DOMU_RAMDISK[$i]}"
+        then
+            echo "ramdisk=\"/boot/${DOMU_RAMDISK[$i]}\"" >> $dest
+        fi
+
+        if [ -z "${DOMU_CMD[$i]}" ]
+        then
+            DOMU_CMD[$i]="console=hvc0"
+        fi
+        if [[ ! ${DOMU_CMD[$i]} =~ root= ]]
+        then
+            if test -z "${DOMU_ROOTFS[$i]}"
+            then
+                DOMU_CMD[$i]="${DOMU_CMD[$i]} root=/dev/ram0" >> $dest
+            else
+                DOMU_CMD[$i]="${DOMU_CMD[$i]} root=/dev/xvda" >> $dest
+            fi
+        fi
+        echo "extra=\"${DOMU_CMD[$i]}\"" >> $dest
+        if test "${DOMU_ROOTFS[$i]}"
+        then
+            add_rootfs $n
+            echo "disk=[\"$retval,,xvda\"]" >> $dest
+        fi
+
+        n=$(( $n + 1 ))
+        i=$(( $i + 1 ))
+    done
+
+    umount $DESTDIR/part/disk$j
+}
+
 function add_partition()
 {
     local rootfs="$1"
@@ -157,6 +243,20 @@ check_depends
 
 source "$CFG_FILE"
 
+i=0
+while test $i -lt $NUM_DOMUS
+do
+    if test -z "${DOMU_MEM[$i]}"
+    then
+        DOMU_MEM[$i]=512
+    fi
+    if test -z "${DOMU_VCPUS[$i]}"
+    then
+        DOMU_VCPUS[$i]=1
+    fi
+    i=$(( $i + 1 ))
+done
+
 offset=$((2*1024*1024))
 _part1_size=`stat -L --printf="%s" $UBOOT_OUT/$XEN`
 _part1_size=$(( $_part1_size + `stat -L --printf="%s" $UBOOT_OUT/$DOM0_KERNEL` ))
@@ -294,6 +394,7 @@ j=2
 if test "$DOM0_ROOTFS"
 then
     write_rootfs 2 "$DOM0_ROOTFS"
+    generate_domU_configs 2
     j=$(( $j + 1 ))
 fi
 
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