From f7186bfd9626363c4217c25db82eb851da81882a Mon Sep 17 00:00:00 2001
From: vishnu <vishnusentha@gmail.com>
Date: Thu, 9 Jul 2026 17:02:20 -0700
Subject: [PATCH 1/3] nvidia: work around GCC 16.1.x ICE compiling flcn_ls10.c

GCC 16.1.x's instruction scheduler (sched2 RTL pass) segfaults with
an internal compiler error while compiling _flcnDmemTransfer_LS10()
in common/nvswitch/kernel/ls10/flcn_ls10.c at the default optimization
level. This is a GCC codegen bug specific to this function's shape,
not a defect in the source.

Disable the two GCC instruction-scheduling passes
(-fno-schedule-insns[2]) for this single translation unit only, gated
to GCC >= 16.0.0 via the existing nv-compiler.sh version check. This
unblocks builds on GCC 16 toolchains without disabling scheduling
anywhere else in nv-kernel.o, and is a no-op on all other compilers/
versions.

Fixes #1213
---
 src/nvidia/Makefile | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/nvidia/Makefile b/src/nvidia/Makefile
index 0e13f2e99..d08282758 100644
--- a/src/nvidia/Makefile
+++ b/src/nvidia/Makefile
@@ -76,6 +76,22 @@ CFLAGS += -fno-common
 CFLAGS += -ffreestanding
 CFLAGS += -fno-stack-protector
 
+##############################################################################
+# GCC 16.1.x's instruction scheduler can crash with an internal compiler
+# error (segfault during the "sched2" RTL pass) while compiling
+# _flcnDmemTransfer_LS10() in flcn_ls10.c at the default optimization level.
+# This is a compiler bug, not a problem with the source; disable the two
+# GCC instruction-scheduling passes for this single translation unit to
+# avoid triggering it, without giving up scheduling anywhere else in the
+# build. See https://github.com/NVIDIA/open-gpu-kernel-modules/issues/1213
+##############################################################################
+FLCN_LS10_CC_TYPE := $(call GET_COMPILER_TYPE, $(CC))
+ifeq ($(FLCN_LS10_CC_TYPE),gcc)
+  ifeq ($(shell $(VERSION_MK_DIR)/nv-compiler.sh version_is_at_least $(CC) 160000),1)
+    $(call BUILD_OBJECT_LIST,$(SRC_COMMON)/nvswitch/kernel/ls10/flcn_ls10.c): CFLAGS += -fno-schedule-insns2 -fno-schedule-insns
+  endif
+endif
+
 ifeq ($(TARGET_ARCH),x86_64)
   CFLAGS += -msoft-float
   CFLAGS += -mno-red-zone

From c0c94e9e10c4157aee64984bc070fa76e9e8b8c4 Mon Sep 17 00:00:00 2001
From: vishnu <vishnusentha@gmail.com>
Date: Thu, 9 Jul 2026 17:02:20 -0700
Subject: [PATCH 2/3] ci: add workflow to verify GCC16 flcn_ls10 fix

---
 .github/workflows/verify-gcc16-fix.yml | 27 ++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 .github/workflows/verify-gcc16-fix.yml

diff --git a/.github/workflows/verify-gcc16-fix.yml b/.github/workflows/verify-gcc16-fix.yml
new file mode 100644
index 000000000..26dde8318
--- /dev/null
+++ b/.github/workflows/verify-gcc16-fix.yml
@@ -0,0 +1,27 @@
+name: verify-gcc16-fix
+
+on:
+  push:
+    branches: [ fix-gcc16-ice-flcn-ls10 ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install GCC 16
+        run: |
+          sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
+          sudo apt-get update
+          sudo apt-get install -y gcc-16 g++-16
+          gcc-16 --version
+
+      - name: Install build deps + matching kernel headers
+        run: |
+          sudo apt-get install -y build-essential libelf-dev "linux-headers-$(uname -r)"
+
+      - name: Build kernel modules with GCC 16
+        run: |
+          make modules -j$(nproc) CC=gcc-16

From 32dddd120ea5e7d387f80b87d5d32e905e3b2022 Mon Sep 17 00:00:00 2001
From: vishnu <vishnusentha@gmail.com>
Date: Thu, 9 Jul 2026 17:02:20 -0700
Subject: [PATCH 3/3] ci: remove verification-only workflow before PR

---
 .github/workflows/verify-gcc16-fix.yml | 27 --------------------------
 1 file changed, 27 deletions(-)
 delete mode 100644 .github/workflows/verify-gcc16-fix.yml

diff --git a/.github/workflows/verify-gcc16-fix.yml b/.github/workflows/verify-gcc16-fix.yml
deleted file mode 100644
index 26dde8318..000000000
--- a/.github/workflows/verify-gcc16-fix.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-name: verify-gcc16-fix
-
-on:
-  push:
-    branches: [ fix-gcc16-ice-flcn-ls10 ]
-  workflow_dispatch:
-
-jobs:
-  build:
-    runs-on: ubuntu-24.04
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Install GCC 16
-        run: |
-          sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
-          sudo apt-get update
-          sudo apt-get install -y gcc-16 g++-16
-          gcc-16 --version
-
-      - name: Install build deps + matching kernel headers
-        run: |
-          sudo apt-get install -y build-essential libelf-dev "linux-headers-$(uname -r)"
-
-      - name: Build kernel modules with GCC 16
-        run: |
-          make modules -j$(nproc) CC=gcc-16