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Introduction

Google has traditionally been against upgrading the compiler as it comes with new warnings and potentially changes behavior. However, these are actually good reasons to upgrade, they help shake out undefined behavior.

Process

In order to compile with a newer version of GCC, you'll need to do a few modifications to your kernel in addition to a new toolchain. I recommend using the ones available from Bootlin.

1. Remove gcc-wrapper and any instances of -Werror: gcc-wrapper is CAF's shitty way of enabling -Werror, which is unnecessary since regular -Werror will suffice. We need to remove it for the time being because there will be new warnings to fix. Pick Google's revert of it (3.18, 4.4) then remove any other instances of -Werror (such as in prima, qcacld-2.0, and qc

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#!/usr/bin/env bash

function die() {
    echo
    echo -e "\033[01;31m${1}\033[0m"
    echo
    exit 1
}

REPOS=( "fw-api" "qcacld-3.0" "qca-wifi-host-cmn" )

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build/powerpc/bad/arch/powerpc/kvm/book3s_hv_nested.o:     file format elf64-powerpc


Disassembly of section .text:

0000000000000000 <.kvmhv_save_hv_regs>:
       0:	7c 08 02 a6 	mflr    r0
       4:	fb e1 ff f8 	std     r31,-8(r1)
       8:	f8 01 00 10 	std     r0,16(r1)

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Reset all files that conflict but keep the non-conflicted ones:

for i in $(git status | grep "both modified" | awk '{print $3}'); do git reset HEAD $i && git checkout -- $i; done



Delete all branches but one

for i in $(git ls-remote -q | grep "refs/head" | cut -d '/' -f 3 | awk '!(/^<BRANCH_NAME_TO_KEEP>$/)'); do git push origin :$i; done

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      1 arch/x86/kernel/kprobes/core.c:959:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 arch/x86/kernel/uprobes.c:1015:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 arch/x86/kvm/cpuid.c:335:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 arch/x86/kvm/vmx/vmx.c:6005:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 block/compat_ioctl.c:282:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 block/ioprio.c:76:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 drivers/accessibility/braille/braille_console.c:249:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 drivers/acpi/sbshc.c:234:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
      1 drivers/ata/libata-eh.c:2814:4: warning: 

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wget https://www.samba.org/ftp/ccache/ccache-3.3.4.tar.gz && tar -xvf ccache-3.3.4.tar.gz && cd ccache-3.3.4 && ./configure && sudo make -j$( grep "^processor" /proc/cpuinfo | wc -l ) install && cd .. && rm -rf ccache-3.3.4*

git clone https://github.com/ninja-build/ninja && cd ninja && ./configure.py --bootstrap && sudo cp -v ninja /usr/local/bin && cd .. && rm -rf ninja

which ninja && which ccache

ccache -V && ninja --version

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• Kernel:

  • https://github.com/nathanchance/op5/commit/0e57a984b7360b2c437447ebae4aea132c96b1a5
  • https://github.com/nathanchance/op5/commit/5c4a84970fd272464434ee8ce15f267613516302
  • https://github.com/nathanchance/op5/commit/3dcbed55373cf53b837936b5656c5dd18e86a9bf

• Device tree in BoardConfig.mk:

  • KBUILD_COMPILER_STRING := whatever you want the string to say
    • Example: KBUILD_COMPILER_STRING := Android (4679922 based on r326829) clang version 7.0.1 (based on LLVM 7.0.1svn)

• export KBUILD_COMPILER_STRING

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Intel Core i7-7700:

arm:multi_v7_defconfig | Success in 9 minutes and 20 seconds

arm:allyesconfig | Success in 43 minutes and 4 seconds

arm64:defconfig | Success in 12 minutes and 38 seconds

arm64:allyesconfig | Success in 48 minutes and 19 seconds

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From 93926cb441d2c82c31be82ab4078c6750b88cffb Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Sun, 30 Sep 2018 18:35:46 -0700
Subject: [PATCH 1/6] DO-NOT-UPSTREAM: Disable GCOV_KERNEL for Clang

Patches currently in testing, just don't want to add them to my stack.

Link: https://github.com/ClangBuiltLinux/linux/issues/17
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

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From 8c16eb5d852c426449c35f5c638fa0241de59900 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Mon, 10 Dec 2018 17:59:43 -0700
Subject: [PATCH 1/4] DO-NOT-UPSTREAM: arm: Don't select HAVE_FUNCTION_TRACER
 with Clang

Link: https://github.com/ClangBuiltLinux/linux/issues/35
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 arch/arm/Kconfig | 2 +-