Add Rosetta and shared directories

README.md

@@ -1,3 +1,65 @@
+# Rosetta Support for Linux guests
+
+This fork adds a commandline option `-g <rosetta directory share tag>` to specify the name of the directory share tag
+used to expose the Rosetta virtiofs directory share to the arm64 Linux guest. The tag can be any name you choose so long
+as it conforms to virtiofs naming conventions.
+
+The virtiofs directory share contains a single linux/arm64 executable named `rosetta`. This executable is an amd64
+emulator which uses the native Rosetta functionality on MacOS to execute amd64 Linux binaries on the arm64 host
+running Apple Silicon.
+
+To actually make use of it in your arm64 Linux guest you must explicitly register a custom binfmt handler in the arm64
+Linux guest by following the installation steps below.
+
+Example usage of `vftool` with `-g ROSETTA`:
+```shell
+vftool/build/vftool -k vmlinux -i initrd -g ROSETTA -d root.img -d varlibdocker.img -m 8192 -p 6 -t 0 -a "root=/dev/vda" "$@"
+```
+
+## PREREQUISITES
+The `binfmt-support` Ubuntu package must be installed in the arm64 Linux guest; this package contains the required
+`update-binfmts` tool.
+```shell
+% sudo apt install binfmt-support
+```
+
+## INSTALLATION
+Run these commands in your arm64 Linux guest on every boot:
+```shell
+% mkdir /tmp/rosetta
+% sudo mount -t virtiofs ROSETTA /tmp/rosetta
+% sudo /usr/sbin/update-binfmts --install rosetta /tmp/rosetta/rosetta \
+    --magic "\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x3e\x00" \
+    --mask "\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff" \
+    --credentials yes --preserve no --fix-binary yes
+```
+
+The token `ROSETTA` in the `mount` command above MUST MATCH the tag name given to vftool `-g` commandline option.
+
+You may see this error on first use of `update-binfmts`; ignore it and repeat the command and it should succeed.
+```
+update-binfmts: warning: unable to close /proc/sys/fs/binfmt_misc/register: No such file or directory
+update-binfmts: warning: unable to enable binary format rosetta
+update-binfmts: exiting due to previous errors
+```
+
+If you intend to use `docker` in the arm64 Linux guest to run containers with the `linux/amd64` platform, it's a good
+idea to set this environment variable in your MacOS host for the MacOS `docker` client to use as a default:
+
+```shell
+export DOCKER_DEFAULT_PLATFORM=linux/amd64
+```
+
+This environment variable could also be specified in the `/lib/systemd/system/docker.service` systemd unit file on the
+arm64 Linux guest by adding this line to the `[Service]` stanza:
+
+```ini
+Environment=DOCKER_DEFAULT_PLATFORM=linux/amd64
+```
+
+## Original README follows
+
+---
 #  Virtualization.framework tool (vftool)
 
 Here lies a _really minimalist_ and very noddy command-line wrapper to run VMs in the macOS Big Sur Virtualization.framework.
@@ -38,6 +100,7 @@ The following command-line arguments are supported:
     -i <initrd path>
     -d <disc image path>
     -c <CDROM image path>
+    -s <shared dir path>[:<tag>[:{ro, rw}]]
     -b <bridged ethernet interface>
     -p <number of processors>
     -m <memory size in MB>
@@ -50,6 +113,14 @@ The `-t` option permits the console to either use stdin/stdout (option `0`), or
 
 Multiple disc images can be attached by using several `-d` or `-c` options.  The discs are attached in the order they are given on the command line, which should then influence which device they appear as.  For example, `-d foo -d bar -c blah` will create three virtio-blk devices, `/dev/vda`, `/dev/vdb`, `/dev/vdc` attached to _foo_, _bar_ and _blah_ respectively.  Up to 8 discs can be attached.
 
+Up to 8 shared directories may be attached with the `-s` option. They are each labelled with a tag;
+if none is specified, the directory name is used. In they guest VM, they may be mounted using:
+```
+mount -t virtiofs <tag> <mount point>
+```
+Note that this requires virtiofs support, which is available in recent distributions such as Ubuntu
+22.04. Directories may be specified as read only by adding the `:ro` suffix.
+
 The kernel should be uncompressed.  The initrd may be a gz.  Disc images are raw/flat files (nothing fancy like qcow2).
 
 When starting vftool, you will see output similar to:

vftool/main.m

@@ -24,12 +24,19 @@
 #define VERSION "v0.3 10/12/2020"
 
 #define MAX_DISCS   8
-
+#define MAX_SHARES  8
+
 struct disc_info {
     NSString    *path;
     bool        readOnly;
 };
 
+struct share_info {
+    NSString    *path;     // Path on host system
+    NSString    *tag;      // Tag on guest system
+    bool        readOnly;
+};
+
 /* ******************************************************************** */
 /* PTY management*/
 
@@ -96,7 +103,10 @@ static int createPty(bool waitForConnection)
                                                   NSString *initrd_path,
                                                   struct disc_info *dinfo,
                                                   unsigned int num_discs,
-                                                  NSString *bridged_eth)
+                                                  struct share_info *sinfo,
+                                                  unsigned int num_shares,
+                                                  NSString *bridged_eth,
+                                                  NSString *rosetta_tag)
 {
     /* **************************************************************** */
     /* Linux bootloader setup:
@@ -210,6 +220,51 @@ static int createPty(bool waitForConnection)
 
     [conf setStorageDevices:discs];
 
+    // Shared directories
+    NSArray *shares = @[];
+
+    for (unsigned int i = 0; i < num_shares; i++) {
+        NSLog(@"+++ Attaching shared directory '%@' with tag '%@' with readOnly=%@ \n",
+                sinfo[i].path, sinfo[i].tag, sinfo[i].readOnly ? @"YES" : @"NO");
+        NSURL *shareURL = [NSURL fileURLWithPath:sinfo[i].path];
+        VZSharedDirectory *sharedDirectory = [[VZSharedDirectory alloc]
+                                              initWithURL: shareURL
+                                              readOnly: sinfo[i].readOnly];
+
+        VZSingleDirectoryShare *singleDirectoryShare = [[VZSingleDirectoryShare alloc]
+                                                        initWithDirectory: sharedDirectory];
+
+        VZVirtioFileSystemDeviceConfiguration *share_conf = [[VZVirtioFileSystemDeviceConfiguration alloc]
+                                                              initWithTag: sinfo[i].tag];
+        share_conf.share = singleDirectoryShare;
+        shares = [shares arrayByAddingObject:share_conf];
+    }
+    [conf setDirectorySharingDevices:shares];
+
+    // expose the Rosetta directory share:
+    NSString *tag = @"ROSETTA";
+
+    // expose the Rosetta directory share as value of rosetta_tag NSString:
+    if (rosetta_tag) {
+        NSError *validationError;
+        if (![VZVirtioFileSystemDeviceConfiguration validateTag:rosetta_tag error:&validationError]) {
+            // Handle validation error here.
+            NSLog(@"-- Configuration validation failure! %@\n", validationError);
+            return nil;
+        }
+
+        VZLinuxRosettaDirectoryShare *rosettaDirectoryShare = [[VZLinuxRosettaDirectoryShare alloc] initWithError:&validationError];
+        if (validationError) {
+            NSLog(@"-- Configuration validation failure! %@\n", validationError);
+            return nil;
+        }
+
+        VZVirtioFileSystemDeviceConfiguration *fileSystemDevice = [[VZVirtioFileSystemDeviceConfiguration alloc] initWithTag:rosetta_tag];
+        fileSystemDevice.share = rosettaDirectoryShare;
+
+        conf.directorySharingDevices = @[fileSystemDevice];
+    }
+
     return conf;
 }
 
@@ -219,17 +274,20 @@ static void usage(const char *me)
     fprintf(stderr, "vftool version " VERSION "\n\n"
                     "Syntax:\n\t%s <options>\n\n"
                     "Options:\n"
-                    "\t-k <kernel path>                 [REQUIRED]\n"
+                    "\t-k <kernel path>                         [REQUIRED]\n"
                     "\t-a <kernel cmdline arguments>\n"
                     "\t-i <initrd path>\n"
                     "\t-d <disc image path>\n"
-                    "\t-c <CDROM image path>            (As -d, but read-only)\n"
-                    "\t-b <bridged ethernet interface>  (Default NAT)\n"
-                    "\t-p <number of processors>        (Default 1)\n"
-                    "\t-m <memory size in MB>           (Default 512MB)\n"
-                    "\t-t <tty type>                    (0 = stdio, 1 = pty (default))\n"
+                    "\t-c <CDROM image path>                    (As -d, but read-only)\n"
+                    "\t-s <shared dir path>[:<tag>[:{ro, rw}]]  (default tag: dir name,\n"
+                    "\t                                          default mode: read/write, at most %d shares) \n"
+                    "\t-b <bridged ethernet interface>          (Default NAT)\n"
+                    "\t-p <number of processors>                (Default 1)\n"
+                    "\t-m <memory size in MB>                   (Default 512MB)\n"
+                    "\t-t <tty type>                            (0 = stdio, 1 = pty (default))\n"
+                    "\t-g <rosetta directory share tag>\n"
                     "\n\tSpecify multiple discs with multiple -d/-c options, in order (max %d)\n",
-                    me, MAX_DISCS);
+                    me, MAX_SHARES, MAX_DISCS);
 }
 
 
@@ -242,15 +300,19 @@ int main(int argc, char *argv[])
         NSString *disc_path = NULL;
         NSString *cdrom_path = NULL;
         NSString *eth_if = NULL;
+        NSString *rosetta_tag = NULL;
         unsigned int cpus = 0;
         unsigned int mem = 0;
         unsigned int tty_type = 1;
 
         struct disc_info dinfo[MAX_DISCS];
         unsigned int num_discs = 0;
 
+        struct share_info sinfo[MAX_SHARES];
+        unsigned int num_shares = 0;
+
         int ch;
-        while ((ch = getopt(argc, argv, "k:a:i:d:c:b:p:m:t:h")) != -1) {
+        while ((ch = getopt(argc, argv, "k:a:i:d:c:s:b:p:m:t:g:h")) != -1) {
             switch (ch) {
                 case 'k':
                     kern_path = [NSString stringWithUTF8String:optarg];
@@ -272,6 +334,40 @@ int main(int argc, char *argv[])
                     dinfo[num_discs].readOnly = (ch == 'c');
                     num_discs++;
                     break;
+                case 's':
+                    if (num_shares > MAX_SHARES-1) {
+                        usage(argv[0]);
+                        fprintf(stderr, "\nError: Too many shared directories specified (max %d)\n\n", MAX_SHARES);
+                        return 1;
+                    }
+
+                    NSString *share_string = [NSString stringWithUTF8String:optarg];
+                    NSArray *share_components = [share_string componentsSeparatedByString:@":"];
+
+                    sinfo[num_shares].path = share_components[0];
+                    sinfo[num_shares].tag = [share_components[0] lastPathComponent];
+                    sinfo[num_shares].readOnly = false;
+
+                    if ([share_components count] > 1){
+                        sinfo[num_shares].tag = share_components[1];
+                    }
+                    if ([share_components count] > 2){
+                        if ([share_components[2] isEqualToString:@"ro"]){
+                            sinfo[num_shares].readOnly = true;
+                        } else if (![share_components[2] isEqualToString:@"rw"]){
+                            usage(argv[0]);
+                            fprintf(stderr, "\nError: Third part of share argument must be one of 'rw' and 'ro', but '%s' was given.\n\n", [share_components[2] UTF8String]);
+                            return 1;
+                        }
+                    }
+                    if ([share_components count] > 3){
+                            usage(argv[0]);
+                            fprintf(stderr, "\nError: Share argument should consist of at most three components separated by ':', but %s was given.\n\n", [share_string UTF8String]);
+                            return 1;
+                    }
+                    num_shares++;
+                    break;
+
                 case 'b':
                     eth_if = [NSString stringWithUTF8String:optarg];
                     break;
@@ -289,6 +385,9 @@ int main(int argc, char *argv[])
                         return 1;
                     }
                     break;
+                case 'g':
+                    rosetta_tag = [NSString stringWithUTF8String:optarg];
+                    break;
 
                 case 'h':
                 default:
@@ -323,8 +422,10 @@ int main(int argc, char *argv[])
         VZVirtualMachineConfiguration *conf = getVMConfig(mem, cpus, tty_type, cmdline,
                                                           kern_path, initrd_path,
                                                           dinfo, num_discs,
-                                                          eth_if);
-
+                                                          sinfo, num_shares,
+                                                          eth_if,
+                                                          rosetta_tag);
+
         if (!conf) {
             NSLog(@"Couldn't create configuration for VM.\n");
             return 1;