From 90f4a2a062c0b06b82a27cc9b94f73431bb9a257 Mon Sep 17 00:00:00 2001
From: Jarrod Johnson <jjohnson2@lenovo.com>
Date: Fri, 11 Apr 2025 12:55:01 -0400
Subject: [PATCH] Improve text console behaviors of Ubuntu and RedHat

RedHat makes grub redundantly handle serial output that firmware
already handles.  If we detect EFI firmware and SPCR ACPI table and
connected serial port, that suggests that firmware will handle.

Ubuntu hates serial console by default, amend it so it can actually
work for serial users.
---
 .../common/profile/scripts/autoconsole        | 117 ++++++++++++++++++
 .../el8/profiles/default/scripts/post.sh      |   5 +
 .../profiles/default/scripts/post.sh          |   4 +
 3 files changed, 126 insertions(+)
 create mode 100644 confluent_osdeploy/common/profile/scripts/autoconsole

diff --git a/confluent_osdeploy/common/profile/scripts/autoconsole b/confluent_osdeploy/common/profile/scripts/autoconsole
new file mode 100644
index 00000000..b37e1df6
--- /dev/null
+++ b/confluent_osdeploy/common/profile/scripts/autoconsole
@@ -0,0 +1,117 @@
+#!/usr/bin/python3
+
+# This script evaluates whether firmware redirection is likely. It uses three cues:
+# - Does the system offer up SPCR? This would indicate that the firmware is doing serial output.
+#   Otherwise, there's no indication that the firmware cares about serial console.
+# - Is the system EFI?  BIOS implementations may not intercept text draw calls after POST exit,
+#   thus even when BIOS tells us serial port is in use, it may not be doing anything when
+#   grub would be running
+# - Is the serial port connected? In the event that firmware indicates serial port, but
+#   serial port is not reporting DCD, then it doesn't look like a comfortable enough scenario
+
+import fcntl
+import os
+import os.path
+import struct
+import subprocess
+import termios
+
+
+addrtoname = {
+    0x3f8: '/dev/ttyS0',
+    0x2f8: '/dev/ttyS1',
+    0x3e8: '/dev/ttyS2',
+    0x2e8: '/dev/ttyS3',
+}
+speedmap = {
+    0: None,
+    3: 9600,
+    4: 19200,
+    6: 57600,
+    7: 115200,
+}
+
+termiobaud = {
+    9600: termios.B9600,
+    19200: termios.B19200,
+    57600: termios.B57600,
+    115200: termios.B115200,
+}
+
+
+def deserialize_grub_rh():
+    if 'console=ttyS' in open('/proc/cmdline').read():
+        return None # User manually indicated serial config
+        # they own the grub behavior too for now
+    grublines = []
+    with open('/etc/default/grub') as grubin:
+        grublines = grubin.read().split('\n')
+    with open('/etc/default/grub', 'w') as grubout:
+        for grubline in grublines:
+            if grubline.startswith('GRUB_TERMINAL'):
+                grubline = grubline.replace('serial ', '')
+            grubout.write(grubline + '\n')
+    subprocess.check_call(['grub2-mkconfig', '-o', '/boot/grub2/grub.cfg'])
+
+def fixup_ubuntu_grub_serial():
+    # Ubuntu aggressively tries to graphics up
+    # grub. We will counter that for serial
+    # They also aggressively hide UI and
+    # block ability to interject. We will
+    # compromise and lean on nodeboot <node> setup
+    # as a means to give someone reasonable shot at
+    # the short timeout
+    with open('/etc/default/grub') as grubin:
+        grublines = grubin.read().split('\n')
+    with open('/etc/default/grub', 'w') as grubout:
+        for grubline in grublines:
+            if grubline.startswith('GRUB_TIMEOUT_STYLE=hidden'):
+                grubline = 'GRUB_TIMEOUT_STYLE=menu'
+            elif grubline.startswith('GRUB_TIMEOUT=0'):
+                grubline = 'GRUB_TIMEOUT=2'
+            elif grubline.startswith('#GRUB_TERMINAL=console'):
+                grubline = grubline.replace('#', '')
+            grubout.write(grubline + '\n')
+    subprocess.check_call(['update-grub'])
+
+def get_serial_config():
+    if not os.path.exists('/sys/firmware/efi'):
+        return None
+    spcr = open("/sys/firmware/acpi/tables/SPCR", "rb")
+    spcr = bytearray(spcr.read())
+    if spcr[8] != 2 or spcr[36] != 0 or spcr[40] != 1:
+        return None
+    address = struct.unpack('<Q', spcr[44:52])[0]
+    tty = None
+    try:
+        tty = addrtoname[address]
+    except KeyError:
+        return None
+    retval = { 'tty': tty }
+    try:
+        retval['speed'] = speedmap[spcr[58]]
+    except KeyError:
+        return None
+    if retval['speed']:
+        ttyf = os.open(tty, os.O_RDWR | os.O_NOCTTY)
+        currattr = termios.tcgetattr(ttyf)
+        currattr[4:6] = [0, termiobaud[retval['speed']]]
+        termios.tcsetattr(ttyf, termios.TCSANOW, currattr)
+    retval['connected'] = bool(struct.unpack('<I', fcntl.ioctl(
+        ttyf, termios.TIOCMGET, '\x00\x00\x00\x00'))[0] & termios.TIOCM_CAR)
+    os.close(ttyf)
+    return retval
+
+def main():
+    autoconscfg = get_serial_config()
+    if not autoconscfg or not autoconscfg['connected']:
+        return
+    if os.path.exists('/etc/redhat-release'):  # redhat family
+        deserialize_grub_rh()
+    elif os.path.exists('/etc/os-release'):
+        with open('/etc/os-release') as osr:
+            if 'Ubuntu' in osr.read():
+                fixup_ubuntu_grub_serial()
+
+if __name__ == '__main__':
+    main()
diff --git a/confluent_osdeploy/el8/profiles/default/scripts/post.sh b/confluent_osdeploy/el8/profiles/default/scripts/post.sh
index f5e9bf84..db1c511d 100644
--- a/confluent_osdeploy/el8/profiles/default/scripts/post.sh
+++ b/confluent_osdeploy/el8/profiles/default/scripts/post.sh
@@ -34,6 +34,11 @@ run_remote_python add_local_repositories
 # run_remote_python will use the appropriate python interpreter path to run the specified script
 # A post.custom is provided to more conveniently hold customizations, see the post.custom file.
 
+# This will do some serial console fixup for bad grub configuration when serial is firmware
+# managed. See script for details
+run_remote_python autoconsole
+
+
 # This will induce server side processing of the syncfile contents if
 # present
 run_remote_python syncfileclient
diff --git a/confluent_osdeploy/ubuntu22.04/profiles/default/scripts/post.sh b/confluent_osdeploy/ubuntu22.04/profiles/default/scripts/post.sh
index a86695ca..72ac0e58 100755
--- a/confluent_osdeploy/ubuntu22.04/profiles/default/scripts/post.sh
+++ b/confluent_osdeploy/ubuntu22.04/profiles/default/scripts/post.sh
@@ -84,6 +84,10 @@ cat /target/etc/confluent/tls/*.pem > /target/etc/confluent/ca.pem
 cat /target/etc/confluent/tls/*.pem > /target/usr/local/share/ca-certificates/confluent.crt
 cat /target/etc/confluent/tls/*.pem > /etc/confluent/ca.pem
 chroot /target update-ca-certificates
+
+# Ubuntu mangles grub function for serial users, undo that mangling
+chroot /target bash -c "source /etc/confluent/functions; run_remote_python autoconsole"
+
 chroot /target bash -c "source /etc/confluent/functions; run_remote_python syncfileclient"
 chroot /target bash -c "source /etc/confluent/functions; run_remote_python confignet"
 chroot /target bash -c "source /etc/confluent/functions; run_remote_parts post.d"