turris omnia: tidy config, remove dead bits

add /boot to the systemConfiguration closure

devices/turris-omnia/default.nix

@@ -2,6 +2,27 @@
   description = ''
     Turris Omnia
     ************
+
+    This is a 32 bit ARMv7 MVEBU device, which is usually shipped with
+    TurrisOS, an OpenWrt-based system. Rather than reformatting the
+    builtin storage, we install Liminix on to the existing btrfs
+    filesystem so that the vendor snapshot/recovery system continues
+    to work (and provides you an easy rollback if you decide you don't
+    like Liminix after all).
+
+    The install process is designed so that you should not need to open
+    the device and add a serial console (although it may be handy
+    for visibility  and in case anything goes wrong). In outline
+
+      1. build a "recovery" system with useful btrfs tools
+      2. boot that system using TFTP or a USB stick
+      3. once booted, mount the real root filesystem on /mnt
+      4. take a snapshot using schnapps, and then delete everything
+      5. use min-copy-closure -d /mnt/@ to copy the real configuration
+         to the device
+      6. reboot into a fully operational system
+
+    Detailed instructions to follow...
   '';
 
   system = {
@@ -30,7 +51,6 @@
       imports = [
         ../../modules/arch/arm.nix
         ../../modules/outputs/tftpboot.nix
-        ../../modules/outputs/ext4fs.nix
         ../../modules/outputs/mbrimage.nix
         ../../modules/outputs/extlinux.nix
       ];
@@ -133,7 +153,6 @@
             "console=ttyS0,115200"
             "pcie_aspm=off" # ath9k pci incompatible with PCIe ASPM
           ];
-          imageFormat = "fit";
         };
         filesystem =
           let
@@ -142,9 +161,9 @@
               name = "wlan-firmware";
               phases = ["installPhase"];
               installPhase = ''
-            mkdir $out
-            cp -r ${pkgs.linux-firmware}/lib/firmware/ath10k/QCA988X $out
-          '';
+                mkdir $out
+                cp -r ${pkgs.linux-firmware}/lib/firmware/ath10k/QCA988X $out
+              '';
             };
           in dir {
             lib = dir {
@@ -176,7 +195,7 @@
           defaultOutput = "mtdimage";
           loadAddress = lim.parseInt "0x00800000"; # "0x00008000";
           entryPoint = lim.parseInt "0x00800000"; # "0x00008000";
-          rootDevice = "/dev/mtdblock0";
+          rootDevice = "/dev/mmcblk0p1";
 
           dts = {
             src = "${config.system.outputs.kernel.modulesupport}/arch/arm/boot/dts/armada-385-turris-omnia.dts";
@@ -210,7 +229,7 @@
               # per
               # https://www.kernel.org/doc/html/latest/networking/dsa/configuration.html#affinity-of-user-ports-to-cpu-ports
               # but apparently OpenWrt doesn't either so maybe it's more
-              # complicated than it looks
+              # complicated than it looks.
 
               wan = link.build {
                 # in armada-38x.dtsi this is eth2. It may be connected to

examples/rotuer.nix

@@ -44,10 +44,12 @@ in rec {
     ../modules/ntp
     ../modules/ssh
     ../modules/outputs/btrfs.nix
-
+    ../modules/outputs/extlinux.nix
   ];
   hostname = "rotuer";
   rootfsType = "btrfs";
+  rootOptions = "subvol=@";
+  boot.loader.extlinux.enable = true;
 
   services.hostap = svc.hostapd.build {
     interface = config.hardware.networkInterfaces.wlan;

modules/base.nix

@@ -47,6 +47,11 @@ in {
         "ubifs"
       ];
     };
+    rootOptions =  mkOption {
+      type = types.nullOr types.str;
+      default = null;
+    };
+
     boot = {
       commandLine = mkOption {
         type = types.listOf types.nonEmptyStr;
@@ -95,7 +100,8 @@ in {
       "root=${config.hardware.rootDevice}"
       "rootfstype=${config.rootfsType}"
       "fw_devlink=off"
-    ];
+    ] ++ lib.optional (config.rootOptions != null) "rootflags=${config.rootOptions}";
+
     users.root = {
       uid = 0; gid= 0; gecos = "Root of all evaluation";
       dir = "/home/root/";

modules/outputs/extlinux.nix

@@ -6,6 +6,7 @@
 }:
 let
   inherit (lib) mkIf mkEnableOption mkOption types concatStringsSep;
+  inherit (pkgs.pseudofile) dir symlink;
   cfg = config.boot.loader.extlinux;
   o = config.system.outputs;
   cmdline = concatStringsSep " " config.boot.commandLine;
@@ -17,7 +18,7 @@ in {
   };
   options.boot.loader.extlinux.enable = mkEnableOption "extlinux";
 
-  config =  { # mkIf cfg.enable {
+  config = mkIf cfg.enable {
     system.outputs.extlinux = pkgs.runCommand "extlinux" {} ''
       mkdir $out
       cd $out
@@ -27,7 +28,7 @@ in {
       mkdir extlinux
       cat > extlinux/extlinux.conf << _EOF
       menu title Liminix
-      timeout 100
+      timeout 40
       label Liminix
         kernel /boot/kernel
         # initrd /boot/initramfs
@@ -35,5 +36,8 @@ in {
         ${if wantsDtb then "fdt /boot/dtb" else ""}
       _EOF
     '';
+    filesystem = dir {
+      boot = symlink config.system.outputs.extlinux;
+    };
   };
 }

pkgs/preinit/opts.h

@@ -0,0 +1,7 @@
+struct root_opts {
+    char *device;
+    char *fstype;
+    char *mount_opts;
+};
+
+void parseopts(char * cmdline, struct root_opts *opts);

pkgs/preinit/parseopts.c

@@ -3,6 +3,9 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "opts.h"
+
+
 static int begins_with(char * str, char * prefix)
 {
 	while(*prefix) {
@@ -36,34 +39,37 @@ char * pr_u32(int32_t input) {
     i+=2;
 
     buf[i] ='\0';
-    write(2, buf, i);
-
-    return buf;
+    if(write(2, buf, i))
+	return buf;
+    else
+	return NULL;
 }
 
+static char *eat_word(char *p)
+{
+    while(*p && (*p != ' ')) p++;
 
-void parseopts(char * cmdline, char **root, char **rootfstype) {
-    *root = 0;
-    *rootfstype = 0;
+    if(*p) {
+	*p = '\0';
+	p++;
+    };
+    return p;
+}
 
+static char * eat_param(char *p, char *param_name, char **out)
+{
+    if(begins_with(p, param_name)) {
+	*out = p + strlen(param_name);
+	p = eat_word(p);
+    };
+    return p;
+}
+
+void parseopts(char * cmdline, struct root_opts *opts) {
     for(char *p = cmdline; *p; p++) {
-	if(begins_with(p, "root=")) {
-	    *root = p + strlen("root=");
-	    while(*p && (*p != ' ')) p++;
-
-	    if(*p) {
-		*p = '\0';
-		p++;
-	    };
-	};
-	if(begins_with(p, "rootfstype=")) {
-	    *rootfstype = p + strlen("rootfstype=");
-	    while(*p && (*p != ' ')) p++;
-	    if(*p) {
-		*p = '\0';
-		p++;
-	    };
-	};
+	p = eat_param(p, "root=", &(opts->device));
+	p = eat_param(p, "rootfstype=", &(opts->fstype));
+	p = eat_param(p, "rootflags=", &(opts->mount_opts));
     };
 }
 
@@ -82,45 +88,59 @@ void parseopts(char * cmdline, char **root, char **rootfstype) {
 
 int main()
 {
-    char * root = "/dev/hda1";
-    char * rootfstype = "xiafs";
+    struct root_opts opts = {
+	.device = "/dev/hda1",
+	.fstype = "xiafs",
+	.mount_opts = NULL
+    };
     char *buf;
 
-    // finds root= and rootfstype= options
-    buf = strdup("liminix console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/ubi0_4 rootfstype=ubifs fw_devlink=off mtdparts=phram0:18M(rootfs) phram.phram=phram0,0x40400000,18874368,65536 root=/dev/mtdblock0 foo");
-    parseopts(buf, &root, &rootfstype);
-    expect_equal(root, "/dev/mtdblock0");
-    expect_equal(rootfstype, "ubifs");
+    // finds root= rootfstype= rootflags= options
+    buf = strdup("liminix console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/ubi0_4 rootfstype=ubifs rootflags=subvol=1 fw_devlink=off mtdparts=phram0:18M(rootfs) phram.phram=phram0,0x40400000,18874368,65536 root=/dev/mtdblock0 foo");
+    memset(&opts, '\0', sizeof opts); parseopts(buf, &opts);
+    expect_equal(opts.device, "/dev/mtdblock0");
+    expect_equal(opts.fstype, "ubifs");
+    expect_equal(opts.mount_opts, "subvol=1");
 
     // in case of duplicates, chooses the latter
     // also: works if the option is end of string
     buf = strdup("liminix console=ttyS0,115200 panic=10 oops=panic init=/bin/init loglevel=8 root=/dev/ubi0_4 rootfstype=ubifs fw_devlink=off mtdparts=phram0:18M(rootfs) phram.phram=phram0,0x40400000,18874368,65536 root=/dev/mtdblock0");
-    parseopts(buf, &root, &rootfstype);
-    expect_equal(root, "/dev/mtdblock0");
-    expect_equal(rootfstype, "ubifs");
+    memset(&opts, '\0', sizeof opts); parseopts(buf, &opts);
+    expect_equal(opts.device, "/dev/mtdblock0");
+    expect_equal(opts.fstype, "ubifs");
 
     // options may appear in either order
     buf = strdup("liminix fw_devlink=off root=/dev/hda1 rootfstype=ubifs  foo");
-    parseopts(buf, &root, &rootfstype);
-    expect_equal(root, "/dev/hda1");
-    expect_equal(rootfstype, "ubifs");
+    memset(&opts, '\0', sizeof opts); parseopts(buf, &opts);
+    expect_equal(opts.device, "/dev/hda1");
+    expect_equal(opts.fstype, "ubifs");
+
+    // works when rootflags is the last option
+    buf = strdup("liminix fw_devlink=off root=/dev/hda1 rootfstype=ubifs rootflags=subvol=@");
+    memset(&opts, '\0', sizeof opts); parseopts(buf, &opts);
+    expect_equal(opts.device, "/dev/hda1");
+    expect_equal(opts.fstype, "ubifs");
+    expect_equal(opts.mount_opts, "subvol=@");
 
     buf = strdup("liminix rootfstype=ubifs fw_devlink=off root=/dev/hda1 foo");
-    parseopts(buf, &root, &rootfstype);
-    expect_equal(rootfstype, "ubifs");
-    expect_equal(root, "/dev/hda1");
+    memset(&opts, '\0', sizeof opts); parseopts(buf, &opts);
+    expect_equal(opts.fstype, "ubifs");
+    expect_equal(opts.device, "/dev/hda1");
 
     // provides NULL for missing options
     buf = strdup("liminix rufustype=ubifs fw_devlink=off foot=/dev/hda1");
-    parseopts(buf, &root, &rootfstype);
-    if(rootfstype) die("expected null rootfstype, got \"%s\"", rootfstype);
-    if(root) die("expected null root, got \"%s\"", root);
+    memset(&opts, '\0', sizeof opts);  parseopts(buf, &opts);
+
+    if(opts.fstype) die("expected null rootfstype, got \"%s\"", opts.fstype);
+    if(opts.device) die("expected null root, got \"%s\"", opts.device);
+    if(opts.mount_opts) die("expected null mount_opts, got \"%s\"", opts.mount_opts);
 
     // provides empty strings for empty options
     buf = strdup("liminix rootfstype= fw_devlink=off root= /dev/hda1");
-    parseopts(buf, &root, &rootfstype);
-    if(strlen(rootfstype)) die("expected empty rootfstype, got \"%s\"", rootfstype);
-    if(strlen(root)) die("expected null root, got \"%s\"", root);
+    memset(&opts, '\0', sizeof opts);  parseopts(buf, &opts);
+
+    if(strlen(opts.fstype)) die("expected empty rootfstype, got \"%s\"", opts.fstype);
+    if(strlen(opts.device)) die("expected null root, got \"%s\"", opts.device);
 
     expect_equal("01", pr_u32(1));
     expect_equal("ab", pr_u32(0xab));

pkgs/preinit/preinit.c

@@ -10,7 +10,7 @@
 
 #include <asm/setup.h>		/* for COMMAND_LINE_SIZE */
 
-void parseopts(char * cmdline, char **root, char **rootfstype);
+#include "opts.h"
 
 #define ERR(x) write(2, x, strlen(x))
 #define AVER(c) do { if(c < 0) { ERR("failed: "  #c ": error=0x" ); pr_u32(errno); ERR("\n"); } } while(0)
@@ -49,8 +49,11 @@ char buf[COMMAND_LINE_SIZE];
 
 int main(int argc, char *argv[], char *envp[])
 {
-    char *rootdevice = 0;
-    char *rootfstype = 0;
+    struct root_opts opts = {
+	.device = NULL,
+	.fstype = NULL,
+	.mount_opts = NULL
+    };
 
     write(1, banner, strlen(banner));
 
@@ -73,16 +76,20 @@ int main(int argc, char *argv[], char *envp[])
 	ERR("failed: open(\"/proc/cmdline\")\n");
 	die();
     }
-    parseopts(buf, &rootdevice, &rootfstype);
+    parseopts(buf, &opts);
 
-    if(rootdevice) {
-	if(!rootfstype) rootfstype = "jffs2"; /* backward compatibility */
+    if(opts.device) {
+	if(!opts.fstype) opts.fstype = "jffs2"; /* backward compatibility */
 	write(1, "rootdevice ", 11);
-	write(1, rootdevice, strlen(rootdevice));
+	write(1, opts.device, strlen(opts.device));
 	write(1, " (", 2);
-	write(1, rootfstype, strlen(rootfstype));
+	write(1, opts.fstype, strlen(opts.fstype));
+	if(opts.mount_opts) {
+	    write(1, ", opts=", 7);
+	    write(1, opts.mount_opts, strlen(opts.mount_opts));
+	}
 	write(1, ")\n", 2);
-	AVER(mount(rootdevice, "/target/persist", rootfstype, 0, NULL));
+	AVER(mount(opts.device, "/target/persist", opts.fstype, 0, opts.mount_opts));
 	AVER(mount("/target/persist/nix", "/target/nix",
 		   "bind", MS_BIND, NULL));
 

pkgs/systemconfig/default.nix

@@ -84,8 +84,19 @@ in attrset:
       #!/bin/sh -e
       prefix=\''${1-/}
       src=\''${prefix}$out
-      mkdir -p \$prefix/persist
-      cp -v -fP \$src/bin/* \$src/etc/* \$prefix/persist
+      dest=\$prefix
+      ${# if we are running on a normal mounted system then
+        # the actual device root is mounted on /persist
+        # and /nix is bind mounted from /persist/nix
+        # (see the code in preinit). So we need to check for this
+        # case otherwise we will install into a ramfs/rootfs
+        ""
+      }
+      if test -d $dest/persist; then dest=$dest/persist; fi
+      cp -v -fP \$src/bin/* \$src/etc/* \$dest
+      ${if attrset ? boot then ''
+        (cd \$prefix && rm ./boot && ln -sf ${lib.strings.removePrefix "/" attrset.boot.target} ./boot)
+      '' else ""}
       EOF
       chmod +x $out/bin/install
     '';