diff --git a/xCAT-server/lib/xcat/plugins/mknb.pm b/xCAT-server/lib/xcat/plugins/mknb.pm
index a3a2a5b91..94702fe66 100644
--- a/xCAT-server/lib/xcat/plugins/mknb.pm
+++ b/xCAT-server/lib/xcat/plugins/mknb.pm
@@ -18,6 +18,14 @@ sub _canonical_genesis_arch {
     return $arch eq 'ppc64el' ? 'ppc64le' : $arch;
 }
 
+# Architectures whose discovery boot goes through UEFI firmware and grub2.
+# mknb writes one grub2 configuration per network for them. The value is the
+# $grub_cpu string reported by that architecture's GRUB build, so one file can
+# carry a menu entry per architecture that shares a network.
+my %GRUB2_DISCOVERY_ARCHES = (
+    riscv64 => 'riscv64',
+);
+
 sub handled_commands {
     return {
         mknb => 'mknb',
@@ -703,6 +711,9 @@ sub process_request {
         }
     } elsif ($arch =~ /ppc/) {
         mkpath("$tftpdir/pxelinux.cfg/p/");
+    } elsif (exists $GRUB2_DISCOVERY_ARCHES{$arch}) {
+        mkpath("$tftpdir/boot/grub2");
+        chmod(0755, "$tftpdir/boot/grub2");
     }
     my $dopxe = 0;
     foreach (keys %{$normnets}) {
@@ -816,11 +827,97 @@ sub process_request {
             print $cfgfile "   initrd http://" . $xcatd_address . "$portsuffix/$initrd_file\n";
             print $cfgfile '   append "xcatd=' . $xcatd_address . ":$xcatdport $consolecmdline\"\n";
             close($cfgfile);
+        } elsif (exists $GRUB2_DISCOVERY_ARCHES{$arch}) {
+            # Unlike the PXELINUX files, which only look at the legacy address of the network,
+            # the discovery configuration is also dropped when the xcatd address chosen for the
+            # network sits on a :noboot interface: it would send Genesis to an interface that
+            # must not serve booting.
+            if (defined($nobootnicips{ $hexnets->{$_} }) or defined($nobootnicips{$xcatd_address})) {
+                unlink("$tftpdir/boot/grub2/grub.cfg-" . uc($_));
+                next;
+            }
+            _write_grub2_discovery_config(
+                tftpdir        => $tftpdir,
+                hexnet         => $_,
+                xcatd_address  => $xcatd_address,
+                xcatdport      => $xcatdport,
+                consolecmdline => $consolecmdline,
+            );
         }
     }
+    if (exists $GRUB2_DISCOVERY_ARCHES{$arch} and !-e "$tftpdir/boot/grub2/grub2.$arch") {
+        # The discovery configurations are only reached through this boot loader, which
+        # xCAT does not build: say so instead of letting the nodes time out in firmware.
+        $callback->({ data => ["Note: $tftpdir/boot/grub2/grub2.$arch is missing; $arch nodes need it to reach these configurations (it is installed by grub2-xcat, or copied from the EL $arch installation media)"] });
+    }
     if ($configfileonly) {
         $callback->({ data => ["Write netboot config file done"] });
     }
 }
 
+# Return the grub2-class architectures whose Genesis kernel and initrd are
+# published under $tftpdir/xcat, as [arch, grub_cpu, kernel, initrd] with the
+# file names relative to the TFTP root.
+
+sub _grub2_discovery_arches {
+    my ($tftpdir) = @_;
+    my @present;
+    foreach my $arch (sort keys %GRUB2_DISCOVERY_ARCHES) {
+        next unless -e "$tftpdir/xcat/genesis.kernel.$arch";
+        my ($initrd) = grep { -e "$tftpdir/$_" }
+          map { "xcat/genesis.fs.$arch.$_" } qw(lzma gz);
+        next unless $initrd;
+        push @present,
+          [ $arch, $GRUB2_DISCOVERY_ARCHES{$arch}, "xcat/genesis.kernel.$arch", $initrd ];
+    }
+    return @present;
+}
+
+# Write the grub2 discovery configuration for one network.
+#
+# grub2.<arch>, net booted from $tftpdir/boot/grub2, looks for grub.cfg-01-<mac>,
+# then grub.cfg-<8 hex digit ip>, then ever shorter prefixes of that ip, and
+# finally grub.cfg. nodeset writes the per-node files (full ip and mac), so a
+# per-network prefix is only reached by clients without a node configuration:
+# discovery. The file is rebuilt from the Genesis artifacts present under
+# $tftpdir/xcat and removed when none are left. Returns the path written.
+sub _write_grub2_discovery_config {
+    my (%args) = @_;
+    my $tftpdir = $args{tftpdir};
+    my $hexnet  = uc($args{hexnet});
+    my $cfgpath = "$tftpdir/boot/grub2/grub.cfg-$hexnet";
+    my @arches  = _grub2_discovery_arches($tftpdir);
+    unless (@arches) {
+        unlink($cfgpath);
+        return;
+    }
+    my $cmdline = "xcatd=$args{xcatd_address}:$args{xcatdport}";
+    if (defined($args{consolecmdline}) and $args{consolecmdline} ne '') {
+        $cmdline .= " $args{consolecmdline}";
+    }
+    my $content = "# xCAT Genesis discovery for network $hexnet - generated by mknb, do not edit\n";
+    $content .= "set default=0\n";
+    $content .= "set timeout=5\n";
+    my $keyword = 'if';
+    foreach my $entry (@arches) {
+        my ($arch, $grub_cpu, $kernel, $initrd) = @{$entry};
+        $content .= "$keyword [ \"\$grub_cpu\" = \"$grub_cpu\" ]; then\n";
+        $content .= "menuentry \"xCAT Genesis $arch\" {\n";
+        $content .= "    linux /$kernel $cmdline BOOTIF=\$net_default_mac\n";
+        $content .= "    initrd /$initrd\n";
+        $content .= "}\n";
+        $keyword = 'elif';
+    }
+    $content .= "fi\n";
+    # nodeset hard-links grub.cfg-<8 hex digit ip> to the node file; on a /32 network that is
+    # this file's name, so replace the name instead of truncating a shared inode.
+    unlink($cfgpath);
+    my $cfg;
+    open($cfg, ">", $cfgpath) or return;
+    print $cfg $content;
+    close($cfg);
+    chmod(0644, $cfgpath);
+    return $cfgpath;
+}
+
 1;