Compiling kernel-3.4.xxx with gcc-9.x. Need some help.

From: Fawad Lateef
Date: Sun Mar 28 2021 - 16:21:52 EST


Hi

I am using an Olimex A20 SOM with NAND and due to some binary blob for
NAND driver, I am stuck with the sunxi kernel 3.4.xxx version. (Repo
here: https://github.com/linux-sunxi/linux-sunxi)

I am currently using buildroot-2016 and gcc-5.5 for building the
kernel and every other package needed.

Now the requirement is to move to the latest version of gcc-9.x, so
that we can have glibc++ provided by the gcc-9.1 toolchain.

Main problem for moving to later versions of buildroot is the kernel
3.4 which we couldn't to work with gcc-6 a few years ago _but_ now the
gcc-9.1 requirement is mandatory so now have to look into compiling
linux-3.4 with gcc-9.1 or above.

Now I need some help.

-- Is it realistic to expect 3.4 kernel compiling and boot
successfully with gcc-9.1?
-- Secondly, till now I am able to compile until the point when its
going to generate the vmlinuz image, it failed with error at LD stage:
arm-none-linux-gnueabihf-ld: no machine record defined

Last few lines from compile log:

-------------------------------------------------------------------------------
include/linux/init.h:267:24: note: in expansion of macro ‘__initcall’
267 | #define module_init(x) __initcall(x);
| ^~~~~~~~~~
net/sunrpc/auth_gss/auth_gss.c:1721:1: note: in expansion of macro ‘module_init’
1721 | module_init(init_rpcsec_gss)
| ^~~~~~~~~~~
In file included from include/linux/kernel.h:20,
from include/linux/spinlock.h:55,
from include/linux/mmzone.h:7,
from include/linux/gfp.h:4,
from include/linux/slab.h:12,
from net/sunrpc/auth_gss/svcauth_gss.c:40:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
LD net/sunrpc/auth_gss/auth_rpcgss.o
LD net/sunrpc/auth_gss/built-in.o
LD net/sunrpc/built-in.o
LD net/built-in.o
LD vmlinux.o
MODPOST vmlinux.o
GEN .version
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
In file included from include/linux/kernel.h:20,
from include/linux/cache.h:4,
from include/linux/time.h:7,
from include/linux/stat.h:60,
from include/linux/module.h:10,
from init/version.c:10:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
LD init/built-in.o
LD .tmp_vmlinux1
arm-none-linux-gnueabihf-ld: no machine record defined
Makefile:875: recipe for target '.tmp_vmlinux1' failed
make: *** [.tmp_vmlinux1] Error 1
-------------------------------------------------------------------------------


After some investigation I found that the MACHINE_START macro from
arch/arm/include/asm/mach/arch.h is optimised by compiler and removed
from the object file during compilation of
"arch/arm/plat-sunxi/core.c" due to the error here:

---------------------------------------------------------------

flateef@flateef-XPS-13-9360:~/src/tmp/linux-custom-venus-gc-9.2$ make
ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabihf- EXTRAVERSION=-custom1
uImage LOADADDR="0x40008000" -j4
CHK include/linux/version.h
CHK include/generated/utsrelease.h
make[1]: 'include/generated/mach-types.h' is up to date.
CALL scripts/checksyscalls.sh
CHK include/generated/compile.h
CC arch/arm/plat-sunxi/core.o
In file included from include/linux/kernel.h:20,
from arch/arm/plat-sunxi/core.c:20:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
In file included from include/linux/scatterlist.h:10,
from include/linux/dma-mapping.h:9,
from arch/arm/plat-sunxi/core.c:24:
arch/arm/plat-sunxi/core.c: In function ‘sw_irq_unmask’:
arch/arm/plat-sunxi/core.c:287:14: warning: left shift count >= width
of type [-Wshift-count-overflow]
287 | writel((1 << SW_INT_IRQNO_ENMI), SW_INT_IRQ_PENDING_REG0);
| ^~
/home/flateef/src/tmp/linux-custom-venus-gc-9.2/arch/arm/include/asm/io.h:52:88:
note: in definition of macro ‘__raw_writel’
52 | #define __raw_writel(v,a) (__chk_io_ptr(a), *(volatile
unsigned int __force *)(a) = (v))
|
^
include/linux/byteorder/generic.h:87:21: note: in expansion of macro
‘__cpu_to_le32’
87 | #define cpu_to_le32 __cpu_to_le32
| ^~~~~~~~~~~~~
/home/flateef/src/tmp/linux-custom-venus-gc-9.2/arch/arm/include/asm/io.h:244:36:
note: in expansion of macro ‘writel_relaxed’
244 | #define writel(v,c) ({ __iowmb(); writel_relaxed(v,c); })
| ^~~~~~~~~~~~~~
arch/arm/plat-sunxi/core.c:287:4: note: in expansion of macro ‘writel’
287 | writel((1 << SW_INT_IRQNO_ENMI), SW_INT_IRQ_PENDING_REG0);
| ^~~~~~
In file included from arch/arm/plat-sunxi/core.c:53:
At top level:
/home/flateef/src/tmp/linux-custom-venus-gc-9.2/arch/arm/include/asm/mach/arch.h:69:34:
warning: ‘__mach_desc_SUN7I’ defined but not used
[-Wunused-const-variable=]
69 | static const struct machine_desc __mach_desc_##_type \
| ^~~~~~~~~~~~
arch/arm/plat-sunxi/core.c:424:1: note: in expansion of macro ‘MACHINE_START’
424 | MACHINE_START(SUN7I, "sun7i")
| ^~~~~~~~~~~~~
/home/flateef/src/tmp/linux-custom-venus-gc-9.2/arch/arm/include/asm/mach/arch.h:69:34:
warning: ‘__mach_desc_SUN5I’ defined but not used
[-Wunused-const-variable=]
69 | static const struct machine_desc __mach_desc_##_type \
| ^~~~~~~~~~~~
arch/arm/plat-sunxi/core.c:410:1: note: in expansion of macro ‘MACHINE_START’
410 | MACHINE_START(SUN5I, "sun5i")
| ^~~~~~~~~~~~~
/home/flateef/src/tmp/linux-custom-venus-gc-9.2/arch/arm/include/asm/mach/arch.h:69:34:
warning: ‘__mach_desc_SUN4I’ defined but not used
[-Wunused-const-variable=]
69 | static const struct machine_desc __mach_desc_##_type \
| ^~~~~~~~~~~~
arch/arm/plat-sunxi/core.c:396:1: note: in expansion of macro ‘MACHINE_START’
396 | MACHINE_START(SUN4I, "sun4i")
| ^~~~~~~~~~~~~
LD arch/arm/plat-sunxi/built-in.o
LD vmlinux.o
MODPOST vmlinux.o
GEN .version
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
In file included from include/linux/kernel.h:20,
from include/linux/cache.h:4,
from include/linux/time.h:7,
from include/linux/stat.h:60,
from include/linux/module.h:10,
from init/version.c:10:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
LD init/built-in.o
LD .tmp_vmlinux1
arm-none-linux-gnueabihf-ld: no machine record defined
Makefile:875: recipe for target '.tmp_vmlinux1' failed
make: *** [.tmp_vmlinux1] Error 1

---------------------------------------------------------------

I modified the MACHINE_START macro in arch/arm/include/asm/mach/arch.h
and added "__attribute__((used))" so it became:

static const struct machine_desc __mach_desc_##_type
__attribute__((used)) \

And I managed to get the vmlinux image.

-------------------------------------------------------------


arch/arm/mm/mmu.c:919:1: note: in expansion of macro ‘early_param’
919 | early_param("vmalloc", early_vmalloc);
| ^~~~~~~~~~~
include/linux/init.h:241:33: warning: ‘__setup_noalign_setup’ defined
but not used [-Wunused-variable]
241 | static struct obs_kernel_param __setup_##unique_id \
| ^~~~~~~~
include/linux/init.h:247:2: note: in expansion of macro ‘__setup_param’
247 | __setup_param(str, fn, fn, 0)
| ^~~~~~~~~~~~~
arch/arm/mm/mmu.c:175:1: note: in expansion of macro ‘__setup’
175 | __setup("noalign", noalign_setup);
| ^~~~~~~
include/linux/init.h:241:33: warning: ‘__setup_early_ecc’ defined but
not used [-Wunused-variable]
241 | static struct obs_kernel_param __setup_##unique_id \
| ^~~~~~~~
include/linux/init.h:252:2: note: in expansion of macro ‘__setup_param’
252 | __setup_param(str, fn, fn, 1)
| ^~~~~~~~~~~~~
arch/arm/mm/mmu.c:165:1: note: in expansion of macro ‘early_param’
165 | early_param("ecc", early_ecc);
| ^~~~~~~~~~~
include/linux/init.h:241:33: warning: ‘__setup_early_nowrite’ defined
but not used [-Wunused-variable]
241 | static struct obs_kernel_param __setup_##unique_id \
| ^~~~~~~~
include/linux/init.h:252:2: note: in expansion of macro ‘__setup_param’
252 | __setup_param(str, fn, fn, 1)
| ^~~~~~~~~~~~~
arch/arm/mm/mmu.c:154:1: note: in expansion of macro ‘early_param’
154 | early_param("nowb", early_nowrite);
| ^~~~~~~~~~~
include/linux/init.h:241:33: warning: ‘__setup_early_nocache’ defined
but not used [-Wunused-variable]
241 | static struct obs_kernel_param __setup_##unique_id \
| ^~~~~~~~
include/linux/init.h:252:2: note: in expansion of macro ‘__setup_param’
252 | __setup_param(str, fn, fn, 1)
| ^~~~~~~~~~~~~
arch/arm/mm/mmu.c:145:1: note: in expansion of macro ‘early_param’
145 | early_param("nocache", early_nocache);
| ^~~~~~~~~~~
include/linux/init.h:241:33: warning: ‘__setup_early_cachepolicy’
defined but not used [-Wunused-variable]
241 | static struct obs_kernel_param __setup_##unique_id \
| ^~~~~~~~
include/linux/init.h:252:2: note: in expansion of macro ‘__setup_param’
252 | __setup_param(str, fn, fn, 1)
| ^~~~~~~~~~~~~
arch/arm/mm/mmu.c:136:1: note: in expansion of macro ‘early_param’
136 | early_param("cachepolicy", early_cachepolicy);
| ^~~~~~~~~~~
AS arch/arm/kernel/head.o
LD arch/arm/kernel/built-in.o
AS arch/arm/mm/cache-v7.o
AS arch/arm/mm/tlb-v7.o
AS arch/arm/mm/proc-v7.o
LD arch/arm/mm/built-in.o
AS arch/arm/lib/copy_page.o
AS arch/arm/lib/csumpartialcopyuser.o
AR arch/arm/lib/lib.a
LD vmlinux.o
MODPOST vmlinux.o
GEN .version
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
In file included from include/linux/kernel.h:20,
from include/linux/cache.h:4,
from include/linux/time.h:7,
from include/linux/stat.h:60,
from include/linux/module.h:10,
from init/version.c:10:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
LD init/built-in.o
LD .tmp_vmlinux1
KSYM .tmp_kallsyms1.S
AS .tmp_kallsyms1.o
LD .tmp_vmlinux2
KSYM .tmp_kallsyms2.S
AS .tmp_kallsyms2.o
LD vmlinux
SYSMAP System.map
SYSMAP .tmp_System.map
OBJCOPY arch/arm/boot/Image
Kernel: arch/arm/boot/Image is ready
AS arch/arm/boot/compressed/head.o
XZKERN arch/arm/boot/compressed/piggy.xzkern
CC arch/arm/boot/compressed/misc.o
CC arch/arm/boot/compressed/decompress.o
CC arch/arm/boot/compressed/string.o
In file included from include/linux/kernel.h:20,
from
arch/arm/boot/compressed/../../../../lib/xz/xz_private.h:15,
from
arch/arm/boot/compressed/../../../../lib/decompress_unxz.c:145,
from arch/arm/boot/compressed/decompress.c:50:
include/linux/log2.h:22:1: warning: ignoring attribute ‘noreturn’
because it conflicts with attribute ‘const’ [-Wattributes]
22 | int ____ilog2_NaN(void);
| ^~~
SHIPPED arch/arm/boot/compressed/lib1funcs.S
SHIPPED arch/arm/boot/compressed/ashldi3.S
AS arch/arm/boot/compressed/lib1funcs.o
AS arch/arm/boot/compressed/ashldi3.o
AS arch/arm/boot/compressed/piggy.xzkern.o
LD arch/arm/boot/compressed/vmlinux
OBJCOPY arch/arm/boot/zImage
Kernel: arch/arm/boot/zImage is ready
UIMAGE arch/arm/boot/uImage
Image Name: Linux-3.4.113-custom1
Created: Sun Mar 28 20:27:03 2021
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1869496 Bytes = 1825.68 KiB = 1.78 MiB
Load Address: 40008000
Entry Point: 40008000
Image arch/arm/boot/uImage is ready


-----------------------------------------------------------------------------


-- I still can't boot the kernel on the platform. I believe its
because there were lots of warning like above (unused const variables
etc) and might have removed some other code/functions OR macros?

So please suggest what I can do for compiling working kernel-3.4 with gcc-9.

Thanks in advance,

-- Fawad Lateef