From d56dd5688127f8fe860b11e5e6a7e8c28ad24549 Mon Sep 17 00:00:00 2001
From: Steve Baker <sbaker@redhat.com>
Date: Tue, 11 Apr 2023 15:49:03 +1200
Subject: [PATCH] Allow custom console=tty0 argument

The bootloader element now has variable
DIB_BOOTLOADER_VIRTUAL_TERMINAL to customize or suppress the
console=tty0 kernel argument.

This is proposed to allow console=tty0 to be removed entirely as it is
causing significant performance degredation in DPDK environments.

Change-Id: Iba2ee5b8a6b4acdd236a770550dffd29c784ce11
Related: rhbz#2179366
---
 diskimage_builder/elements/bootloader/README.rst |  5 +++++
 .../environment.d/10-bootloader-default-cmdline  |  7 +++++++
 .../elements/bootloader/finalise.d/50-bootloader | 16 +++++++++++-----
 releasenotes/notes/tty0-d01980dce4ed7786.yaml    |  5 +++++
 4 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 releasenotes/notes/tty0-d01980dce4ed7786.yaml

diff --git a/diskimage_builder/elements/bootloader/README.rst b/diskimage_builder/elements/bootloader/README.rst
index c786ee0b..306410de 100644
--- a/diskimage_builder/elements/bootloader/README.rst
+++ b/diskimage_builder/elements/bootloader/README.rst
@@ -17,3 +17,8 @@ Arguments
 * ``DIB_BOOTLOADER_SERIAL_CONSOLE`` sets the serial device to be
   used as a console. It defaults to ``hvc0`` for PowerPC, 
   ``ttyAMA0,115200`` for ARM64, otherwise ``ttyS0,115200``.
+
+* ``DIB_BOOTLOADER_VIRTUAL_TERMINAL`` sets the virtual terminal be
+  used as a console. It defaults to ``tty0``. When explicitly set
+  to an empty string then no virtual terminal console kernel argument
+  is added.
diff --git a/diskimage_builder/elements/bootloader/environment.d/10-bootloader-default-cmdline b/diskimage_builder/elements/bootloader/environment.d/10-bootloader-default-cmdline
index a5176b80..598f5980 100644
--- a/diskimage_builder/elements/bootloader/environment.d/10-bootloader-default-cmdline
+++ b/diskimage_builder/elements/bootloader/environment.d/10-bootloader-default-cmdline
@@ -1,2 +1,9 @@
 export DIB_BOOTLOADER_DEFAULT_CMDLINE=${DIB_BOOTLOADER_DEFAULT_CMDLINE:-"nofb nomodeset gfxpayload=text"}
 export DIB_BOOTLOADER_SERIAL_CONSOLE=${DIB_BOOTLOADER_SERIAL_CONSOLE:-""}
+if [ ! -v DIB_BOOTLOADER_VIRTUAL_TERMINAL ]; then
+    # DIB_BOOTLOADER_VIRTUAL_TERMINAL is unset
+    export DIB_BOOTLOADER_VIRTUAL_TERMINAL=tty0
+else
+    # DIB_BOOTLOADER_VIRTUAL_TERMINAL is set to empty string or other value
+    export DIB_BOOTLOADER_VIRTUAL_TERMINAL=${DIB_BOOTLOADER_VIRTUAL_TERMINAL}
+fi
diff --git a/diskimage_builder/elements/bootloader/finalise.d/50-bootloader b/diskimage_builder/elements/bootloader/finalise.d/50-bootloader
index 64f06810..5cb14c2d 100755
--- a/diskimage_builder/elements/bootloader/finalise.d/50-bootloader
+++ b/diskimage_builder/elements/bootloader/finalise.d/50-bootloader
@@ -135,17 +135,23 @@ fi
 
 
 if [[ -n "${DIB_BOOTLOADER_SERIAL_CONSOLE}" ]]; then
-    SERIAL_CONSOLE="${DIB_BOOTLOADER_SERIAL_CONSOLE}"
+    SERIAL_CONSOLE="console=${DIB_BOOTLOADER_SERIAL_CONSOLE}"
 elif [[ "powerpc ppc64 ppc64le" =~ "$ARCH" ]]; then
     # Serial console on Power is hvc0
-    SERIAL_CONSOLE="hvc0"
+    SERIAL_CONSOLE="console=hvc0"
 elif [[ "arm64" =~ "$ARCH" ]]; then
-    SERIAL_CONSOLE="ttyAMA0,115200"
+    SERIAL_CONSOLE="console=ttyAMA0,115200"
 else
-    SERIAL_CONSOLE="ttyS0,115200"
+    SERIAL_CONSOLE="console=ttyS0,115200"
 fi
 
-GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=${SERIAL_CONSOLE} no_timer_check"
+if [[ -n "${DIB_BOOTLOADER_VIRTUAL_TERMINAL}" ]]; then
+    VIRTUAL_TERMINAL="console=${DIB_BOOTLOADER_VIRTUAL_TERMINAL}"
+else
+    VIRTUAL_TERMINAL=""
+fi
+
+GRUB_CMDLINE_LINUX_DEFAULT="${VIRTUAL_TERMINAL} ${SERIAL_CONSOLE} no_timer_check"
 echo "GRUB_CMDLINE_LINUX_DEFAULT=\"${GRUB_CMDLINE_LINUX_DEFAULT} ${DIB_BOOTLOADER_DEFAULT_CMDLINE} ${BOOT_FS} ${BOOT_FIPS}\"" >>/etc/default/grub
 echo 'GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"' >>/etc/default/grub
 
diff --git a/releasenotes/notes/tty0-d01980dce4ed7786.yaml b/releasenotes/notes/tty0-d01980dce4ed7786.yaml
new file mode 100644
index 00000000..b29244eb
--- /dev/null
+++ b/releasenotes/notes/tty0-d01980dce4ed7786.yaml
@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    The bootloader element now has variable DIB_BOOTLOADER_VIRTUAL_TERMINAL to
+    customize or suppress the console=tty0 kernel argument.
\ No newline at end of file