37f2447049 ("kbuild: fix linker feature test macros when cross .."): BUG: kernel hang in early-boot stage, last printk: Decompressing Linux...
1:23 a.m.
Greetings,
0day kernel testing robot got the below dmesg and the first bad commit is
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild
commit 37f24470495731e8b5cfd29164e346ca9d3c0632
Author: Nick Desaulniers <ndesaulniers(a)google.com>
AuthorDate: Fri Oct 27 13:13:43 2017 -0700
Commit: Masahiro Yamada <yamada.masahiro(a)socionext.com>
CommitDate: Sat Oct 28 23:45:19 2017 +0900
kbuild: fix linker feature test macros when cross compiling with Clang
I was not seeing my linker flags getting added when using ld-option when
cross compiling with Clang. Upon investigation, this seems to be due to
a difference in how GCC vs Clang handle cross compilation.
GCC is configured at build time to support one backend, that is implicit
when compiling. Clang is explicit via the use of `-target <triple>` and
ships with all supported backends by default.
GNU Make feature test macros that compile then link will always fail
when cross compiling with Clang unless Clang's triple is passed along to
the compiler. For example:
$ clang -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
unknown architecture of input file `temp.o' is incompatible with
aarch64 output
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000400078
$ echo $?
1
$ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to 00000000004002e4
$ echo $?
0
This causes conditional checks that invoke $(CC) without the target
triple, then $(LD) on the result, to always fail.
Suggested-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers(a)google.com>
Reviewed-by: Matthias Kaehlcke <mka(a)chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
4467d3f62b kbuild: shrink .cache.mk when it exceeds 1000 lines
37f2447049 kbuild: fix linker feature test macros when cross compiling with Clang
+---------------------------------------------------------------------+------------+------------+
| | 4467d3f62b |
37f2447049 |
+---------------------------------------------------------------------+------------+------------+
| boot_successes | 45 | 0
|
| boot_failures | 1 | 15
|
| BUG:kernel_reboot-without-warning_in_test_stage | 1 |
|
| BUG:kernel_hang_in_early-boot_stage,last_printk:Decompressing_Linux | 0 | 15
|
+---------------------------------------------------------------------+------------+------------+
output_len: 0x02878090
kernel_total_size: 0x03212000
Decompressing Linux...
# HH:MM RESULT GOOD BAD
GOOD_BUT_DIRTY DIRTY_NOT_BAD
git bisect start a31e7b0dd1c980f8f842421bd373b6afc24c537f
bb176f67090ca54869fc1262c913aa69d2ede070 --
git bisect bad 692704061fb6f80f037821c9ade25e6ee9d17e07 # 08:38 B 0 7 50 15
Merge 'nf-next/master' into devel-spot-201710290439
git bisect bad 24dd4080b9c6b1a1a0a7bf973aab35f9cbf12c8d # 08:56 B 0 9 21 0
Merge 'nfs/multipath_tcp' into devel-spot-201710290439
git bisect good de878dafcdae7a7ffd23447434ed0c1a7041df0c # 09:25 G 11 0 0 0
Merge 'masahiroy/kbuild' into devel-spot-201710290439
git bisect bad 147b60216364d0894b8311056262421d876f4404 # 10:01 B 0 11 23 0
Merge 'chao-linux/f2fs-dev' into devel-spot-201710290439
git bisect bad 6b86583a4f515543d235803943209d79c562f4cc # 10:29 B 0 5 26 8
Merge 'masahiroy/for-next' into devel-spot-201710290439
git bisect good f7b0acea7951ca21d8da74ee840dc83edbca95ba # 11:03 G 11 0 0 0
kbuild: rpm-pkg: do not force -jN in submake
git bisect good 8808232e8600605b81763d2972124fd24561aaad # 11:37 G 11 0 0 0
kbuild: Cache a few more calls to the compiler
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:01 B 0 11 23 0
kbuild: fix linker feature test macros when cross compiling with Clang
git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:20 G 11 0 0 1
kbuild: shrink .cache.mk when it exceeds 1000 lines
# first bad commit: [37f24470495731e8b5cfd29164e346ca9d3c0632] kbuild: fix linker feature
test macros when cross compiling with Clang
git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:24 G 31 0 0 1
kbuild: shrink .cache.mk when it exceeds 1000 lines
# extra tests with CONFIG_DEBUG_INFO_REDUCED
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:49 B 0 2 14 0
kbuild: fix linker feature test macros when cross compiling with Clang
# extra tests on HEAD of linux-devel/devel-spot-201710290439
git bisect bad a31e7b0dd1c980f8f842421bd373b6afc24c537f # 12:55 B 0 59 119 0
0day head guard for 'devel-spot-201710290439'
# extra tests on tree/branch masahiroy/kbuild
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:59 B 0 15 27 0
kbuild: fix linker feature test macros when cross compiling with Clang
# extra tests with first bad commit reverted
git bisect good 09508094eac49ab7db0f797d9c8fb8a0ae555e26 # 13:23 G 11 0 0 0
Revert "kbuild: fix linker feature test macros when cross compiling with
Clang"
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/lkp Intel Corporation
12:05 p.m.
+ Rahul
On Sat, Oct 28, 2017 at 10:23 PM, kernel test robot
<fengguang.wu(a)intel.com> wrote:
Greetings,
0day kernel testing robot got the below dmesg and the first bad commit is
https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild
commit 37f24470495731e8b5cfd29164e346ca9d3c0632
Author: Nick Desaulniers <ndesaulniers(a)google.com>
AuthorDate: Fri Oct 27 13:13:43 2017 -0700
Commit: Masahiro Yamada <yamada.masahiro(a)socionext.com>
CommitDate: Sat Oct 28 23:45:19 2017 +0900
kbuild: fix linker feature test macros when cross compiling with Clang
I was not seeing my linker flags getting added when using ld-option when
cross compiling with Clang. Upon investigation, this seems to be due to
a difference in how GCC vs Clang handle cross compilation.
GCC is configured at build time to support one backend, that is implicit
when compiling. Clang is explicit via the use of `-target <triple>` and
ships with all supported backends by default.
GNU Make feature test macros that compile then link will always fail
when cross compiling with Clang unless Clang's triple is passed along to
the compiler. For example:
$ clang -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
unknown architecture of input file `temp.o' is incompatible with
aarch64 output
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000400078
$ echo $?
1
$ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to 00000000004002e4
$ echo $?
0
This causes conditional checks that invoke $(CC) without the target
triple, then $(LD) on the result, to always fail.
Suggested-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers(a)google.com>
Reviewed-by: Matthias Kaehlcke <mka(a)chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
4467d3f62b kbuild: shrink .cache.mk when it exceeds 1000 lines
37f2447049 kbuild: fix linker feature test macros when cross compiling with Clang
+---------------------------------------------------------------------+------------+------------+
| | 4467d3f62b |
37f2447049 |
+---------------------------------------------------------------------+------------+------------+
| boot_successes | 45 | 0
|
| boot_failures | 1 | 15
|
| BUG:kernel_reboot-without-warning_in_test_stage | 1 |
|
| BUG:kernel_hang_in_early-boot_stage,last_printk:Decompressing_Linux | 0 | 15
|
+---------------------------------------------------------------------+------------+------------+
output_len: 0x02878090
kernel_total_size: 0x03212000
Decompressing Linux...
# HH:MM RESULT GOOD BAD
GOOD_BUT_DIRTY DIRTY_NOT_BAD
git bisect start a31e7b0dd1c980f8f842421bd373b6afc24c537f
bb176f67090ca54869fc1262c913aa69d2ede070 --
git bisect bad 692704061fb6f80f037821c9ade25e6ee9d17e07 # 08:38 B 0 7 50
15 Merge 'nf-next/master' into devel-spot-201710290439
git bisect bad 24dd4080b9c6b1a1a0a7bf973aab35f9cbf12c8d # 08:56 B 0 9 21
0 Merge 'nfs/multipath_tcp' into devel-spot-201710290439
git bisect good de878dafcdae7a7ffd23447434ed0c1a7041df0c # 09:25 G 11 0 0
0 Merge 'masahiroy/kbuild' into devel-spot-201710290439
git bisect bad 147b60216364d0894b8311056262421d876f4404 # 10:01 B 0 11 23
0 Merge 'chao-linux/f2fs-dev' into devel-spot-201710290439
git bisect bad 6b86583a4f515543d235803943209d79c562f4cc # 10:29 B 0 5 26
8 Merge 'masahiroy/for-next' into devel-spot-201710290439
git bisect good f7b0acea7951ca21d8da74ee840dc83edbca95ba # 11:03 G 11 0 0
0 kbuild: rpm-pkg: do not force -jN in submake
git bisect good 8808232e8600605b81763d2972124fd24561aaad # 11:37 G 11 0 0
0 kbuild: Cache a few more calls to the compiler
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:01 B 0 11 23
0 kbuild: fix linker feature test macros when cross compiling with Clang
git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:20 G 11 0 0
1 kbuild: shrink .cache.mk when it exceeds 1000 lines
# first bad commit: [37f24470495731e8b5cfd29164e346ca9d3c0632] kbuild: fix linker feature
test macros when cross compiling with Clang
git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:24 G 31 0 0
1 kbuild: shrink .cache.mk when it exceeds 1000 lines
# extra tests with CONFIG_DEBUG_INFO_REDUCED
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:49 B 0 2 14
0 kbuild: fix linker feature test macros when cross compiling with Clang
# extra tests on HEAD of linux-devel/devel-spot-201710290439
git bisect bad a31e7b0dd1c980f8f842421bd373b6afc24c537f # 12:55 B 0 59 119
0 0day head guard for 'devel-spot-201710290439'
# extra tests on tree/branch masahiroy/kbuild
git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:59 B 0 15 27
0 kbuild: fix linker feature test macros when cross compiling with Clang
# extra tests with first bad commit reverted
git bisect good 09508094eac49ab7db0f797d9c8fb8a0ae555e26 # 13:23 G 11 0 0
0 Revert "kbuild: fix linker feature test macros when cross compiling with
Clang"
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/lkp Intel Corporation
--
Thanks,
~Nick Desaulniers
12:11 p.m.
No panics or warnings, simply a:
[ 116.382366] softdog: Initiating system reboot
Probably what I can do is grab that config, make V=1, then compare
before and after my patch applied to see if different linker flags get
emitted?
On Mon, Oct 30, 2017 at 9:05 AM, Nick Desaulniers
<ndesaulniers(a)google.com> wrote:
+ Rahul
On Sat, Oct 28, 2017 at 10:23 PM, kernel test robot
<fengguang.wu(a)intel.com> wrote:
> Greetings,
>
> 0day kernel testing robot got the below dmesg and the first bad commit is
>
> https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild
>
> commit 37f24470495731e8b5cfd29164e346ca9d3c0632
> Author: Nick Desaulniers <ndesaulniers(a)google.com>
> AuthorDate: Fri Oct 27 13:13:43 2017 -0700
> Commit: Masahiro Yamada <yamada.masahiro(a)socionext.com>
> CommitDate: Sat Oct 28 23:45:19 2017 +0900
>
> kbuild: fix linker feature test macros when cross compiling with Clang
>
> I was not seeing my linker flags getting added when using ld-option when
> cross compiling with Clang. Upon investigation, this seems to be due to
> a difference in how GCC vs Clang handle cross compilation.
>
> GCC is configured at build time to support one backend, that is implicit
> when compiling. Clang is explicit via the use of `-target <triple>` and
> ships with all supported backends by default.
>
> GNU Make feature test macros that compile then link will always fail
> when cross compiling with Clang unless Clang's triple is passed along to
> the compiler. For example:
>
> $ clang -x c /dev/null -c -o temp.o
> $ aarch64-linux-android/bin/ld -E temp.o
> aarch64-linux-android/bin/ld:
> unknown architecture of input file `temp.o' is incompatible with
> aarch64 output
> aarch64-linux-android/bin/ld:
> warning: cannot find entry symbol _start; defaulting to
> 0000000000400078
> $ echo $?
> 1
>
> $ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o
> $ aarch64-linux-android/bin/ld -E temp.o
> aarch64-linux-android/bin/ld:
> warning: cannot find entry symbol _start; defaulting to 00000000004002e4
> $ echo $?
> 0
>
> This causes conditional checks that invoke $(CC) without the target
> triple, then $(LD) on the result, to always fail.
>
> Suggested-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers(a)google.com>
> Reviewed-by: Matthias Kaehlcke <mka(a)chromium.org>
> Signed-off-by: Masahiro Yamada <yamada.masahiro(a)socionext.com>
>
> 4467d3f62b kbuild: shrink .cache.mk when it exceeds 1000 lines
> 37f2447049 kbuild: fix linker feature test macros when cross compiling with Clang
>
+---------------------------------------------------------------------+------------+------------+
> | | 4467d3f62b |
37f2447049 |
>
+---------------------------------------------------------------------+------------+------------+
> | boot_successes | 45 |
0 |
> | boot_failures | 1 |
15 |
> | BUG:kernel_reboot-without-warning_in_test_stage | 1 |
|
> | BUG:kernel_hang_in_early-boot_stage,last_printk:Decompressing_Linux | 0 |
15 |
>
+---------------------------------------------------------------------+------------+------------+
>
> output_len: 0x02878090
> kernel_total_size: 0x03212000
>
> Decompressing Linux...
>
> # HH:MM RESULT GOOD BAD
GOOD_BUT_DIRTY DIRTY_NOT_BAD
> git bisect start a31e7b0dd1c980f8f842421bd373b6afc24c537f
bb176f67090ca54869fc1262c913aa69d2ede070 --
> git bisect bad 692704061fb6f80f037821c9ade25e6ee9d17e07 # 08:38 B 0 7
50 15 Merge 'nf-next/master' into devel-spot-201710290439
> git bisect bad 24dd4080b9c6b1a1a0a7bf973aab35f9cbf12c8d # 08:56 B 0 9
21 0 Merge 'nfs/multipath_tcp' into devel-spot-201710290439
> git bisect good de878dafcdae7a7ffd23447434ed0c1a7041df0c # 09:25 G 11 0
0 0 Merge 'masahiroy/kbuild' into devel-spot-201710290439
> git bisect bad 147b60216364d0894b8311056262421d876f4404 # 10:01 B 0 11
23 0 Merge 'chao-linux/f2fs-dev' into devel-spot-201710290439
> git bisect bad 6b86583a4f515543d235803943209d79c562f4cc # 10:29 B 0 5
26 8 Merge 'masahiroy/for-next' into devel-spot-201710290439
> git bisect good f7b0acea7951ca21d8da74ee840dc83edbca95ba # 11:03 G 11 0
0 0 kbuild: rpm-pkg: do not force -jN in submake
> git bisect good 8808232e8600605b81763d2972124fd24561aaad # 11:37 G 11 0
0 0 kbuild: Cache a few more calls to the compiler
> git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:01 B 0 11
23 0 kbuild: fix linker feature test macros when cross compiling with Clang
> git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:20 G 11 0
0 1 kbuild: shrink .cache.mk when it exceeds 1000 lines
> # first bad commit: [37f24470495731e8b5cfd29164e346ca9d3c0632] kbuild: fix linker
feature test macros when cross compiling with Clang
> git bisect good 4467d3f62b5cfddd20362649d988c18317f8e754 # 12:24 G 31 0
0 1 kbuild: shrink .cache.mk when it exceeds 1000 lines
> # extra tests with CONFIG_DEBUG_INFO_REDUCED
> git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:49 B 0 2
14 0 kbuild: fix linker feature test macros when cross compiling with Clang
> # extra tests on HEAD of linux-devel/devel-spot-201710290439
> git bisect bad a31e7b0dd1c980f8f842421bd373b6afc24c537f # 12:55 B 0 59
119 0 0day head guard for 'devel-spot-201710290439'
> # extra tests on tree/branch masahiroy/kbuild
> git bisect bad 37f24470495731e8b5cfd29164e346ca9d3c0632 # 12:59 B 0 15
27 0 kbuild: fix linker feature test macros when cross compiling with Clang
> # extra tests with first bad commit reverted
> git bisect good 09508094eac49ab7db0f797d9c8fb8a0ae555e26 # 13:23 G 11 0
0 0 Revert "kbuild: fix linker feature test macros when cross compiling with
Clang"
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/lkp Intel Corporation
--
Thanks,
~Nick Desaulniers
--
Thanks,
~Nick Desaulniers
1088
days inactive
1096
days old
3 comments
2 participants
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Nick Desaulniers