Add initial support for making riscv64 images

They'll not be bootable yet, but let's make a start

debian/changelog

@@ -12,6 +12,7 @@ debian-cd (3.2.2) UNRELEASED; urgency=medium
   * Fix counting of images at build time. Closes: #1063858
   * make_disc_trees.pl: if files will not fit on media, fail loudly
     rather than sitting in a loop foreber. Fail properly in #1069682.
+  * Add initial support for making riscv64 images
 
   [ Guido Berhoerster ]
   * Update DebianEdu installer banner and syslinux splash image

tools/boot/trixie/boot-riscv64

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Do install stuff for riscv64
+# Should work with debian-installer (?)
+# $1 is the CD number
+# $2 is the temporary CD build dir
+#
+
+. $BASEDIR/tools/boot/$DI_CODENAME/common.sh
+
+N=$1
+CDDIR=$2
+
+# Common options for all disks
+add_mkisofs_opt $CDDIR/../$N.mkisofs_opts "-J -joliet-long"
+add_mkisofs_opt $CDDIR/../$N.mkisofs_opts "-cache-inodes"
+add_mkisofs_opt $CDDIR/../$N.mkisofs_opts "-l"
+
+# Exit if this is not CD#1/DVD#1
+if [ $N != "1" ]; then
+    exit 0
+fi
+
+if [ "$DI_WWW_HOME" = "default" ]; then
+    DI_WWW_HOME="https://d-i.debian.org/daily-images/riscv64/daily"
+    try_di_image_cache
+else
+    DI_WWW_HOME=$(echo $DI_WWW_HOME | sed "s,%ARCH%,$ARCH,")
+fi
+
+# Not doing anything special here in terms of setting up bootable
+# media *yet*. Let's see what we can do about UEFI boot from USB or
+# similar?
+copy_arch_images

tools/generate_di+k_list

@@ -253,6 +253,17 @@ grub-efi-arm64-signed
 shim-signed
 #endif
 
+#ifdef ARCH_riscv64
+initramfs-tools
+busybox
+zstd
+flash-kernel
+linux-image-riscv64
+grub-efi
+grub-efi-riscv64
+grub-efi-riscv64-bin
+#endif
+
 #ifdef ARCH_sparc
 initramfs-tools
 grub-ieee1275