PKGBUILD: Introduce rt $_preempt option

In an attempt to correctly classify $_cpusched as strictly CPU schedulers, remove both `rt` and `rt-bore` from $_cpusched
option and move it to $_preempt. In fact, this would be more correct and make more sense, since PREEMPT_RT only makes more
code preemptible compared to PREEMPT and doesn't do anything else special.

One of the blockers for this was sourcing the OOT patches that were needed for the i915 module to be compiled, but
this is not a problem as there is a conditional check for rt to not build zfs.

Signed-off-by: Eric Naim <dnaim@cachyos.org>

Author: 1Naim

linux-cachyos-rc/PKGBUILD

@@ -18,8 +18,6 @@ _cachy_config=${_cachy_config-y}
 # 'hardened' - select 'BORE Scheduler hardened' ## kernel with hardened config and hardening patches with the bore scheduler
 # 'cachyos' - select 'CachyOS Default Scheduler (BORE)'
 # 'eevdf' - select 'EEVDF Scheduler'
-# 'rt' - select EEVDF, but includes a series of realtime patches
-# 'rt-bore' - select Burst-Oriented Response Enhancer, but includes a series of realtime patches
 _cpusched=${_cpusched-cachyos}
 
 ### Tweak kernel options prior to a build via nconfig
@@ -76,7 +74,7 @@ _HZ_ticks=${_HZ_ticks-1000}
 ### Full tickless can give higher performances in various cases but, depending on hardware, lower consistency.
 _tickrate=${_tickrate-full}
 
-## Choose between full(low-latency), lazy, voluntary or none
+## Choose between rt(realtime), full(low-latency), lazy, voluntary or none
 _preempt=${_preempt-full}
 
 ### Transparent Hugepages
@@ -224,8 +222,10 @@ if _is_lto_kernel; then
 fi
 
 # WARNING The ZFS module doesn't build with selected RT sched due to licensing issues.
-if [[ "$_cpusched" = "rt" || "$_cpusched" = "rt-bore" ]]; then
+if [ "$_preempt" = "rt" ]; then
     unset _build_zfs
+    # Uncomment this when the patch exists
+    #source+=("${_patchsource}/misc/0001-rt.patch")
 fi
 
 # ZFS support
@@ -263,7 +263,7 @@ fi
 
 ## List of CachyOS schedulers
 case "$_cpusched" in
-    cachyos|bore|rt-bore|hardened) # CachyOS Scheduler (BORE)
+    cachyos|bore|hardened) # CachyOS Scheduler (BORE)
         source+=("${_patchsource}/sched/0001-bore-cachy.patch");;&
     bmq) ## Project C Scheduler
         source+=("${_patchsource}/sched/0001-prjc-cachy.patch");;
@@ -332,8 +332,6 @@ prepare() {
         cachyos|bore|hardened) scripts/config -e SCHED_BORE;;
         bmq) scripts/config -e SCHED_ALT -e SCHED_BMQ;;
         eevdf) ;;
-        rt) scripts/config -d PREEMPT -e PREEMPT_RT;;
-        rt-bore) scripts/config -e SCHED_BORE -d PREEMPT -e PREEMPT_RT;;
         *) _die "The value $_cpusched is invalid. Choose the correct one again.";;
     esac
 
@@ -411,12 +409,8 @@ prepare() {
     echo "Selecting '$_tickrate' tick type..."
 
     ### Select preempt type
-
-    # We should not set up the PREEMPT for RT kernels
-    if [[ "$_cpusched" != "rt" || "$_cpusched" != "rt-bore" ]]; then
-        [ -z "$_preempt" ] && _die "The value is empty. Choose the correct one again."
-
         case "$_preempt" in
+            rt) scripts/config -e PREEMPT_DYNAMIC -e PREEMPT -e PREEMPT_RT;;
             full) scripts/config -e PREEMPT_DYNAMIC -e PREEMPT -d PREEMPT_VOLUNTARY -d PREEMPT_LAZY -d PREEMPT_NONE;;
             lazy) scripts/config -e PREEMPT_DYNAMIC -d PREEMPT -d PREEMPT_VOLUNTARY -e PREEMPT_LAZY -d PREEMPT_NONE;;
             voluntary) scripts/config -d PREEMPT_DYNAMIC -e PREEMPT_VOLUNTARY_BUILD -d PREEMPT -e PREEMPT_VOLUNTARY -d PREEMPT_LAZY -d PREEMPT_NONE;;