From f25c41b4d2ff3f5f8543834d7848913efa4a995b Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Fri, 22 Dec 2023 23:03:07 +0000
Subject: [PATCH] tftpboot: move things around in memory

new layout has rootfs followed by kernel and dtb, so that we
know the rootfs start and size to embed them into the dtb instead
of having to use dummy values and fill them in afterwards
---
 modules/outputs/tftpboot.nix | 51 +++++++++++++++++++-----------------
 1 file changed, 27 insertions(+), 24 deletions(-)

diff --git a/modules/outputs/tftpboot.nix b/modules/outputs/tftpboot.nix
index aaeb936..e8b5edf 100644
--- a/modules/outputs/tftpboot.nix
+++ b/modules/outputs/tftpboot.nix
@@ -60,43 +60,46 @@ in {
           }; in choices.${cfg.kernelFormat};
           cmdline = concatStringsSep " " config.boot.commandLine;
         in
-          pkgs.runCommand "tftpboot" { nativeBuildInputs = [ pkgs.pkgsBuildBuild.dtc ];  } ''
+          pkgs.runCommand "tftpboot" { nativeBuildInputs = with pkgs.pkgsBuildBuild; [ lzma dtc ];  } ''
             mkdir $out
             cd $out
-            ln -s ${o.rootfs} rootfs
-            ln -s ${o.kernel} vmlinux
+            binsize() { local s=$(stat -L -c %s $1); echo $(($s + 0x1000 &(~0xfff))); }
+            binsize64k() { local s=$(stat -L -c %s $1); echo $(($s + 0x10000 &(~0xffff))); }
+            hex() { printf "0x%x" $1; }
+            rootfsStart=${toString cfg.loadAddress}
+            rootfsSize=$(binsize64k ${o.rootfs} )
+            imageStart=$(($rootfsStart + $rootfsSize))
+            imageSize=$(binsize ${image})
+            dtbStart=$(($imageStart + $imageSize))
+            dtbSize=$(binsize ${o.dtb} )
+
             ln -s ${o.manifest} manifest
-            ln -s ${o.kernel.headers} build
+            ln -s ${o.rootfs} rootfs
             ln -s ${image} image
-            uimageSize=$(($(stat -L -c %s ${image}) + 0x1000 &(~0xfff)))
-            rootfsStart=$(printf %x $((${toString cfg.loadAddress} + 0x100000 + $uimageSize   &(~0xfffff) )))
-            rootfsBytes=$(($(stat -L -c %s ${o.rootfs}) + 0x100000 &(~0xfffff)))
-            rootfsBytes=$(($rootfsBytes + ${toString cfg.freeSpaceBytes} ))
-            cmd="mtdparts=phram0:''${rootfsBytes}(rootfs) phram.phram=phram0,0x''${rootfsStart},''${rootfsBytes},${toString config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
 
-            dtbStart=$(printf %x $((${toString cfg.loadAddress} + $rootfsBytes + 0x100000 + $uimageSize )))
-
-            cat ${o.dtb} > $out/dtb
-            address_cells=$(fdtget $out/dtb / '#address-cells')
-            size_cells=$(fdtget $out/dtb / '#size-cells')
+            cat ${o.dtb} > dtb
+            address_cells=$(fdtget dtb / '#address-cells')
+            size_cells=$(fdtget dtb / '#size-cells')
             if [ $address_cells -gt 1 ]; then ac_prefix=0; fi
             if [ $size_cells -gt 1 ]; then sz_prefix=0; fi
 
-            fdtput -p  $out/dtb /reserved-memory '#address-cells' $address_cells
-            fdtput -p  $out/dtb /reserved-memory '#size-cells' $size_cells
-            fdtput -p  $out/dtb /reserved-memory ranges
-            fdtput -p -t s $out/dtb /reserved-memory/phram-rootfs@$rootfsStart compatible phram
-            fdtput -p -t lx $out/dtb /reserved-memory/phram-rootfs@$rootfsStart reg $ac_prefix 0x$rootfsStart $sz_prefix $(printf %x $rootfsBytes)
+            fdtput -p dtb /reserved-memory '#address-cells' $address_cells
+            fdtput -p dtb /reserved-memory '#size-cells' $size_cells
+            fdtput -p dtb /reserved-memory ranges
+            node=$(printf "phram-rootfs@%x" $rootfsStart)
+            fdtput -p -t s dtb /reserved-memory/$node compatible phram
+            fdtput -p -t lx dtb /reserved-memory/$node reg $ac_prefix $(hex $rootfsStart) $sz_prefix $(hex $rootfsBytes)
 
-            # dtc -I dtb -O dts -o /dev/stdout $out/dtb | grep -A10 reserved-mem ; exit 1
-            dtbBytes=$(($(stat -L -c %s $out/dtb) + 0x1000 &(~0xfff)))
+            cmd="mtdparts=phram0:''${rootfsSize}(rootfs) phram.phram=phram0,''${rootfsStart},''${rootfsSize},${toString config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
 
-            cat > $out/boot.scr << EOF
+            # dtc -I dtb -O dts -o /dev/stdout dtb | grep -A10 reserved-mem ; exit 1
+
+            cat > boot.scr << EOF
             setenv serverip ${cfg.serverip}
             setenv ipaddr ${cfg.ipaddr}
             setenv bootargs 'liminix ${cmdline} $cmd'
-            tftpboot 0x${lib.toHexString cfg.loadAddress} result/image ; tftpboot 0x$rootfsStart result/rootfs ; tftpboot 0x$dtbStart result/dtb
-            ${bootCommand} 0x${lib.toHexString cfg.loadAddress} - 0x$dtbStart
+            tftpboot $(hex $imageStart) result/image ; tftpboot $(hex $rootfsStart) result/rootfs ; tftpboot $(hex $dtbStart) result/dtb
+            ${bootCommand} $(hex $imageStart) - $(hex $dtbStart)
             EOF
          '';