liminix-fork/modules/outputs/tftpboot.nix
Daniel Barlow f25c41b4d2 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
2023-12-23 00:05:34 +00:00

108 lines
3.9 KiB
Nix

{
config
, pkgs
, lib
, ...
}:
let
inherit (lib) mkOption types concatStringsSep;
cfg = config.boot.tftp;
in {
imports = [ ../ramdisk.nix ];
options.boot.tftp = {
freeSpaceBytes = mkOption {
type = types.int;
default = 0;
};
kernelFormat = mkOption {
type = types.enum [ "zimage" "uimage" ];
default = "uimage";
};
};
options.system.outputs = {
tftpboot = mkOption {
type = types.package;
description = ''
tftpboot
********
This output is intended for developing on a new device.
It assumes you have a serial connection and a
network connection to the device and that your
build machine is running a TFTP server.
The output is a directory containing kernel and
root filesystem image, and a script :file:`boot.scr` of U-Boot
commands that will load the images into memory and
run them directly,
instead of first writing them to flash. This saves
time and erase cycles.
It uses the Linux `phram <https://github.com/torvalds/linux/blob/master/drivers/mtd/devices/phram.c>`_ driver to emulate a flash device using a segment of physical RAM.
'';
};
};
config = {
boot.ramdisk.enable = true;
system.outputs = rec {
tftpboot =
let
inherit (pkgs.lib.trivial) toHexString;
o = config.system.outputs;
image = let choices = {
uimage = o.uimage;
zimage = o.zimage;
}; in choices.${cfg.kernelFormat};
bootCommand = let choices = {
uimage = "bootm";
zimage = "bootz";
}; in choices.${cfg.kernelFormat};
cmdline = concatStringsSep " " config.boot.commandLine;
in
pkgs.runCommand "tftpboot" { nativeBuildInputs = with pkgs.pkgsBuildBuild; [ lzma dtc ]; } ''
mkdir $out
cd $out
binsize() { local s=$(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.rootfs} rootfs
ln -s ${image} image
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 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 $rootfsBytes)
cmd="mtdparts=phram0:''${rootfsSize}(rootfs) phram.phram=phram0,''${rootfsStart},''${rootfsSize},${toString config.hardware.flash.eraseBlockSize} root=/dev/mtdblock0";
# 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 $(hex $imageStart) result/image ; tftpboot $(hex $rootfsStart) result/rootfs ; tftpboot $(hex $dtbStart) result/dtb
${bootCommand} $(hex $imageStart) - $(hex $dtbStart)
EOF
'';
};
};
}