Hi Thomas
Media-CI has found a couple of new warnings in the latest kernel
version for aarch64 and powerpc. They get fixed with this patch and
before moving I wanted to know if this was under your radar.
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 7dec05dd33b7..65914842fae0 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
ifneq ($(c-gettimeofday-y),)
- CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
+ CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
-Wno-maybe-uninitialized
endif
ifneq ($(c-getrandom-y),)
diff --git a/arch/powerpc/kernel/vdso/Makefile
b/arch/powerpc/kernel/vdso/Makefile
index 8834dfe9d727..4b8d40b1dfeb 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -12,12 +12,12 @@ obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
obj-vdso64 += getrandom-64.o vgetrandom-chacha-64.o
ifneq ($(c-gettimeofday-y),)
- CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
+ CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
-Wno-maybe-uninitialized
# Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code.
That used to be true
# by accident when the VDSO was hand-written asm code, but may not be
now that the VDSO is
# compiler generated. To avoid breaking Go tell GCC not to use r30.
Impact on code
# generation is minimal, it will just use r29 instead.
- CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call
cc-option, -ffixed-r30)
+ CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call
cc-option, -ffixed-r30) -Wno-maybe-uninitialized
endif
ifneq ($(c-getrandom-y),)
https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc
CONFIG_CC_VERSION_TEXT="aarch64-linux-gnu-gcc (Debian 15.2.0-16) 15.2.0"
SYNC include/config/auto.conf
CC arch/arm64/kernel/vdso/vgettimeofday.o
In file included from <command-line>:
In function ‘vdso_set_timespec’,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime_data.constprop’ at
/workdir/lib/vdso/gettimeofday.c:306:7:
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
| ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function
‘__cvdso_clock_gettime_data.constprop’:
/workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here
242 | u64 sec, ns;
| ^~~
In file included from /workdir/lib/vdso/gettimeofday.c:11:
In function ‘__iter_div_u64_rem’,
inlined from ‘vdso_set_timespec’ at /workdir/lib/vdso/gettimeofday.c:104:21,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime_data.constprop’ at
/workdir/lib/vdso/gettimeofday.c:306:7:
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
10 | while (dividend >= divisor) {
| ~~~~~~~~~^~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function
‘__cvdso_clock_gettime_data.constprop’:
/workdir/lib/vdso/gettimeofday.c:242:18: note: ‘ns’ was declared here
242 | u64 sec, ns;
| ^~
LD arch/arm64/kernel/vdso/vdso.so.dbg
VDSOSYM include/generated/vdso-offsets.h
OBJCOPY arch/arm64/kernel/vdso/vdso.so
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
CONFIG_CC_VERSION_TEXT="powerpc64-linux-gnu-gcc (Debian 15.2.0-15) 15.2.0"
SYNC include/config/auto.conf
VDSO32C arch/powerpc/kernel/vdso/vgettimeofday-32.o
In file included from <command-line>:
In function ‘vdso_set_timespec’,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime32_data’ at
/workdir/lib/vdso/gettimeofday.c:327:7:
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
| ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function ‘__cvdso_clock_gettime32_data’:
/workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here
242 | u64 sec, ns;
| ^~~
In file included from /workdir/lib/vdso/gettimeofday.c:11:
In function ‘__iter_div_u64_rem’,
inlined from ‘vdso_set_timespec’ at /workdir/lib/vdso/gettimeofday.c:104:21,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime32_data’ at
/workdir/lib/vdso/gettimeofday.c:327:7:
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
10 | while (dividend >= divisor) {
| ~~~~~~~~~^~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function ‘__cvdso_clock_gettime32_data’:
/workdir/lib/vdso/gettimeofday.c:242:18: note: ‘ns’ was declared here
242 | u64 sec, ns;
| ^~
In function ‘vdso_set_timespec’,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime_data’ at
/workdir/lib/vdso/gettimeofday.c:306:7:
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
| ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function ‘__cvdso_clock_gettime_data’:
/workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here
242 | u64 sec, ns;
| ^~~
In function ‘__iter_div_u64_rem’,
inlined from ‘vdso_set_timespec’ at /workdir/lib/vdso/gettimeofday.c:104:21,
inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2,
inlined from ‘__cvdso_clock_gettime_common’ at
/workdir/lib/vdso/gettimeofday.c:293:10,
inlined from ‘__cvdso_clock_gettime_data’ at
/workdir/lib/vdso/gettimeofday.c:306:7:
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
10 | while (dividend >= divisor) {
| ~~~~~~~~~^~~~~~~~~~
/workdir/lib/vdso/gettimeofday.c: In function ‘__cvdso_clock_gettime_data’:
/workdir/lib/vdso/gettimeofday.c:242:18: note: ‘ns’ was declared here
242 | u64 sec, ns;
| ^~
VDSO32L arch/powerpc/kernel/vdso/vdso32.so.dbg
VDSO32SYM include/generated/vdso32-offsets.h
CC arch/powerpc/kernel/vdso/vgettimeofday-64.o
VDSO64L arch/powerpc/kernel/vdso/vdso64.so.dbg
VDSO64SYM include/generated/vdso64-offsets.h
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
/workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used
uninitialized [-Wmaybe-uninitialized]
./include/vdso/math64.h:10:25: warning: ‘ns’ may be used uninitialized
[-Wmaybe-uninitialized]
Thanks
--
Ricardo RibaldaHi Ricardo, On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: > Media-CI has found a couple of new warnings in the latest kernel > version for aarch64 and powerpc. They get fixed with this patch and > before moving I wanted to know if this was under your radar. Thanks for the report. I was not aware of these so far. > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > index 7dec05dd33b7..65914842fae0 100644 > --- a/arch/arm64/kernel/vdso/Makefile > +++ b/arch/arm64/kernel/vdso/Makefile > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO) > CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO) > > ifneq ($(c-gettimeofday-y),) > - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > -Wno-maybe-uninitialized > endif (...) I'd like to know exactly what is going on before suppressing the warning. It is a non-standard warning, only enabled by *some* of the vDSO builds for some reason. > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc While I was able to download a configuration from this job and also use the same container image, I can not reproduce the issue. Is the configuration the full one or only the template? Could you provide full reproduction steps? > CONFIG_CC_VERSION_TEXT="aarch64-linux-gnu-gcc (Debian 15.2.0-16) 15.2.0" The linked test log shows GCC 14.2, not 15.2. Not that I could reproduce it with either one... > SYNC include/config/auto.conf > CC arch/arm64/kernel/vdso/vgettimeofday.o > In file included from <command-line>: > In function ‘vdso_set_timespec’, > inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2, > inlined from ‘__cvdso_clock_gettime_common’ at > /workdir/lib/vdso/gettimeofday.c:293:10, > inlined from ‘__cvdso_clock_gettime_data.constprop’ at > /workdir/lib/vdso/gettimeofday.c:306:7: > /workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used > uninitialized [-Wmaybe-uninitialized] > 104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); > | ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > /workdir/lib/vdso/gettimeofday.c: In function > ‘__cvdso_clock_gettime_data.constprop’: > /workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here > 242 | u64 sec, ns; > | ^~~ The same pattern is used in some other do_ handlers, which do not generate this warning. I also can't immediately see what is wrong. (...) Thomas
Le 22/04/2026 à 07:56, Thomas Weißschuh a écrit : > Hi Ricardo, > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: >> Media-CI has found a couple of new warnings in the latest kernel >> version for aarch64 and powerpc. They get fixed with this patch and >> before moving I wanted to know if this was under your radar. > > Thanks for the report. I was not aware of these so far. > >> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile >> index 7dec05dd33b7..65914842fae0 100644 >> --- a/arch/arm64/kernel/vdso/Makefile >> +++ b/arch/arm64/kernel/vdso/Makefile >> @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO) >> CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO) >> >> ifneq ($(c-gettimeofday-y),) >> - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) >> + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) >> -Wno-maybe-uninitialized >> endif > > (...) > > I'd like to know exactly what is going on before suppressing the warning. > It is a non-standard warning, only enabled by *some* of the vDSO builds > for some reason. > >> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Flinux-media%2Fusers%2Fribalda%2F-%2Fpipelines%2F1649144%2Ftest_report%3Fjob_name%3Dcross-gcc&data=05%7C02%7Cchristophe.leroy2%40cs-soprasteria.com%7C5c0f15ee20a44072f47108dea0340304%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639124342424606113%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=9Tvp2aYfB02ijxVGLzCOYcMwZlPvqVDufxEporLl1mc%3D&reserved=0 > > While I was able to download a configuration from this job and also use the > same container image, I can not reproduce the issue. Is the configuration the > full one or only the template? > > Could you provide full reproduction steps? > >> CONFIG_CC_VERSION_TEXT="aarch64-linux-gnu-gcc (Debian 15.2.0-16) 15.2.0" > > The linked test log shows GCC 14.2, not 15.2. > Not that I could reproduce it with either one... > >> SYNC include/config/auto.conf >> CC arch/arm64/kernel/vdso/vgettimeofday.o >> In file included from <command-line>: >> In function ‘vdso_set_timespec’, >> inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2, >> inlined from ‘__cvdso_clock_gettime_common’ at >> /workdir/lib/vdso/gettimeofday.c:293:10, >> inlined from ‘__cvdso_clock_gettime_data.constprop’ at >> /workdir/lib/vdso/gettimeofday.c:306:7: >> /workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used >> uninitialized [-Wmaybe-uninitialized] >> 104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); >> | ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> /workdir/lib/vdso/gettimeofday.c: In function >> ‘__cvdso_clock_gettime_data.constprop’: >> /workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here >> 242 | u64 sec, ns; >> | ^~~ > > The same pattern is used in some other do_ handlers, which do not generate this > warning. I also can't immediately see what is wrong. You are likely in a special case where vdso_get_timestamp() returns false without setting &sec, and some versions of GCC and/or CLANG fail to see that vdso_set_timespec() is not called when vdso_get_timestamp() returns false. Christophe
Hi Thomas Thanks for the prompt reply On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh <thomas.weissschuh@linutronix.de> wrote: > > Hi Ricardo, > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: > > Media-CI has found a couple of new warnings in the latest kernel > > version for aarch64 and powerpc. They get fixed with this patch and > > before moving I wanted to know if this was under your radar. > > Thanks for the report. I was not aware of these so far. > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > > index 7dec05dd33b7..65914842fae0 100644 > > --- a/arch/arm64/kernel/vdso/Makefile > > +++ b/arch/arm64/kernel/vdso/Makefile > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO) > > CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO) > > > > ifneq ($(c-gettimeofday-y),) > > - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > -Wno-maybe-uninitialized > > endif > > (...) > > I'd like to know exactly what is going on before suppressing the warning. > It is a non-standard warning, only enabled by *some* of the vDSO builds > for some reason. > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc > > While I was able to download a configuration from this job and also use the > same container image, I can not reproduce the issue. Is the configuration the > full one or only the template? > > Could you provide full reproduction steps? You can try repro with: work/linux $ podman run -v .:/workdir/ --rm -it registry.freedesktop.org/linux-media/media-ci/build:latest $ cd /workdir $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make arch/arm64/kernel/vdso/vgettimeofday.o The gcc version discrepancy is because I the error was due to old gcc version and I was playing around with that... but it fails in both gcc14 and gcc15 You can try with debian testing with work/linux$ podman run -v .:/workdir/ --rm -it debian:testing $ apt-get update $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libssl-dev bc $ cd /workdir $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make arch/arm64/kernel/vdso/vgettimeofday.o Regards! > > > CONFIG_CC_VERSION_TEXT="aarch64-linux-gnu-gcc (Debian 15.2.0-16) 15.2.0" > > The linked test log shows GCC 14.2, not 15.2. > Not that I could reproduce it with either one... > > > SYNC include/config/auto.conf > > CC arch/arm64/kernel/vdso/vgettimeofday.o > > In file included from <command-line>: > > In function ‘vdso_set_timespec’, > > inlined from ‘do_aux’ at /workdir/lib/vdso/gettimeofday.c:266:2, > > inlined from ‘__cvdso_clock_gettime_common’ at > > /workdir/lib/vdso/gettimeofday.c:293:10, > > inlined from ‘__cvdso_clock_gettime_data.constprop’ at > > /workdir/lib/vdso/gettimeofday.c:306:7: > > /workdir/lib/vdso/gettimeofday.c:104:26: warning: ‘sec’ may be used > > uninitialized [-Wmaybe-uninitialized] > > 104 | ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); > > | ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > /workdir/lib/vdso/gettimeofday.c: In function > > ‘__cvdso_clock_gettime_data.constprop’: > > /workdir/lib/vdso/gettimeofday.c:242:13: note: ‘sec’ was declared here > > 242 | u64 sec, ns; > > | ^~~ > > The same pattern is used in some other do_ handlers, which do not generate this > warning. I also can't immediately see what is wrong. > > (...) > > > Thomas -- Ricardo Ribalda
On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote: > On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh > <thomas.weissschuh@linutronix.de> wrote: > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: > > > Media-CI has found a couple of new warnings in the latest kernel > > > version for aarch64 and powerpc. They get fixed with this patch and > > > before moving I wanted to know if this was under your radar. > > > > Thanks for the report. I was not aware of these so far. > > > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > > > index 7dec05dd33b7..65914842fae0 100644 > > > --- a/arch/arm64/kernel/vdso/Makefile > > > +++ b/arch/arm64/kernel/vdso/Makefile > > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO) > > > CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO) > > > > > > ifneq ($(c-gettimeofday-y),) > > > - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > > + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > > -Wno-maybe-uninitialized > > > endif > > > > (...) > > > > I'd like to know exactly what is going on before suppressing the warning. > > It is a non-standard warning, only enabled by *some* of the vDSO builds > > for some reason. > > > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc > > > > While I was able to download a configuration from this job and also use the > > same container image, I can not reproduce the issue. Is the configuration the > > full one or only the template? > > > > Could you provide full reproduction steps? > > You can try repro with: > > work/linux $ podman run -v .:/workdir/ --rm -it > registry.freedesktop.org/linux-media/media-ci/build:latest > $ cd /workdir > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make > arch/arm64/kernel/vdso/vgettimeofday.o > > The gcc version discrepancy is because I the error was due to old gcc > version and I was playing around with that... but it fails in both > gcc14 and gcc15 Ack. > You can try with debian testing with > work/linux$ podman run -v .:/workdir/ --rm -it debian:testing > $ apt-get update > $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libssl-dev bc > $ cd /workdir > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make > arch/arm64/kernel/vdso/vgettimeofday.o Both reproducers do *not* reproduce the issue for me. (It is more or less exactly what I tried before) Please note that this line does not work in general: $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make arch/arm64/kernel/vdso/vgettimeofday.o The vDSO object files can not be built in this way like regular kernel object files and will produce a compiler error, but not the one under discussion. Instead the vDSO on arm64 is built during the 'make prepare' phase. (Other architectures work differently, of course...) (...) Thomas
Hi Thomas On Wed, 22 Apr 2026 at 15:32, Thomas Weißschuh <thomas.weissschuh@linutronix.de> wrote: > > On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote: > > On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh > > <thomas.weissschuh@linutronix.de> wrote: > > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote: > > > > Media-CI has found a couple of new warnings in the latest kernel > > > > version for aarch64 and powerpc. They get fixed with this patch and > > > > before moving I wanted to know if this was under your radar. > > > > > > Thanks for the report. I was not aware of these so far. > > > > > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile > > > > index 7dec05dd33b7..65914842fae0 100644 > > > > --- a/arch/arm64/kernel/vdso/Makefile > > > > +++ b/arch/arm64/kernel/vdso/Makefile > > > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO) > > > > CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO) > > > > > > > > ifneq ($(c-gettimeofday-y),) > > > > - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > > > + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) > > > > -Wno-maybe-uninitialized > > > > endif > > > > > > (...) > > > > > > I'd like to know exactly what is going on before suppressing the warning. > > > It is a non-standard warning, only enabled by *some* of the vDSO builds > > > for some reason. > > > > > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc > > > > > > While I was able to download a configuration from this job and also use the > > > same container image, I can not reproduce the issue. Is the configuration the > > > full one or only the template? > > > > > > Could you provide full reproduction steps? > > > > You can try repro with: > > > > work/linux $ podman run -v .:/workdir/ --rm -it > > registry.freedesktop.org/linux-media/media-ci/build:latest > > $ cd /workdir > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make > > arch/arm64/kernel/vdso/vgettimeofday.o > > > > The gcc version discrepancy is because I the error was due to old gcc > > version and I was playing around with that... but it fails in both > > gcc14 and gcc15 > > Ack. > > > You can try with debian testing with > > work/linux$ podman run -v .:/workdir/ --rm -it debian:testing > > $ apt-get update > > $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libssl-dev bc > > $ cd /workdir > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make > > arch/arm64/kernel/vdso/vgettimeofday.o > > Both reproducers do *not* reproduce the issue for me. > (It is more or less exactly what I tried before) Ok, I think I found what is going on. media-ci was forcing KCFLAGS=-Wmaybe-uninitialized https://gitlab.freedesktop.org/linux-media/media-ci/-/blob/main/test-build.sh?ref_type=heads#L29 And something has changed in the kernel in the last version that triggers a (hopefully) false positive. can you try with: CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make KCFLAGS=-Wmaybe-uninitialized allyesconfig CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make KCFLAGS=-Wmaybe-uninitialized prepare ? > > Please note that this line does not work in general: > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make arch/arm64/kernel/vdso/vgettimeofday.o > > The vDSO object files can not be built in this way like regular kernel object > files and will produce a compiler error, but not the one under discussion. > Instead the vDSO on arm64 is built during the 'make prepare' phase. > (Other architectures work differently, of course...) > > (...) > > > Thomas -- Ricardo Ribalda
On Wed, Apr 22, 2026 at 04:06:45PM +0800, Ricardo Ribalda wrote:
> On Wed, 22 Apr 2026 at 15:32, Thomas Weißschuh
> <thomas.weissschuh@linutronix.de> wrote:
> >
> > On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote:
> > > On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh
> > > <thomas.weissschuh@linutronix.de> wrote:
> > > > On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote:
> > > > > Media-CI has found a couple of new warnings in the latest kernel
> > > > > version for aarch64 and powerpc. They get fixed with this patch and
> > > > > before moving I wanted to know if this was under your radar.
> > > >
> > > > Thanks for the report. I was not aware of these so far.
> > > >
> > > > > diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
> > > > > index 7dec05dd33b7..65914842fae0 100644
> > > > > --- a/arch/arm64/kernel/vdso/Makefile
> > > > > +++ b/arch/arm64/kernel/vdso/Makefile
> > > > > @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
> > > > > CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
> > > > >
> > > > > ifneq ($(c-gettimeofday-y),)
> > > > > - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> > > > > + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
> > > > > -Wno-maybe-uninitialized
> > > > > endif
> > > >
> > > > (...)
> > > >
> > > > I'd like to know exactly what is going on before suppressing the warning.
> > > > It is a non-standard warning, only enabled by *some* of the vDSO builds
> > > > for some reason.
> > > >
> > > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/pipelines/1649144/test_report?job_name=cross-gcc
> > > >
> > > > While I was able to download a configuration from this job and also use the
> > > > same container image, I can not reproduce the issue. Is the configuration the
> > > > full one or only the template?
> > > >
> > > > Could you provide full reproduction steps?
> > >
> > > You can try repro with:
> > >
> > > work/linux $ podman run -v .:/workdir/ --rm -it
> > > registry.freedesktop.org/linux-media/media-ci/build:latest
> > > $ cd /workdir
> > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
> > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
> > > arch/arm64/kernel/vdso/vgettimeofday.o
> > >
> > > The gcc version discrepancy is because I the error was due to old gcc
> > > version and I was playing around with that... but it fails in both
> > > gcc14 and gcc15
> >
> > Ack.
> >
> > > You can try with debian testing with
> > > work/linux$ podman run -v .:/workdir/ --rm -it debian:testing
> > > $ apt-get update
> > > $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libssl-dev bc
> > > $ cd /workdir
> > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
> > > $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
> > > arch/arm64/kernel/vdso/vgettimeofday.o
> >
> > Both reproducers do *not* reproduce the issue for me.
> > (It is more or less exactly what I tried before)
>
>
> Ok, I think I found what is going on. media-ci was forcing
> KCFLAGS=-Wmaybe-uninitialized
>
> https://gitlab.freedesktop.org/linux-media/media-ci/-/blob/main/test-build.sh?ref_type=heads#L29
>
> And something has changed in the kernel in the last version that
> triggers a (hopefully) false positive.
>
> can you try with:
>
> CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
> KCFLAGS=-Wmaybe-uninitialized allyesconfig
> CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
> KCFLAGS=-Wmaybe-uninitialized prepare
That works!
The warning was introduced in ed78b7b2c5ae ("vdso/gettimeofday: Add a helper to
read the sequence lock of a time namespace aware clock").
It is *not* a false-positive, specifically:
do {
if (vdso_read_begin_timens(vc, &seq)) {
vd = __arch_get_vdso_u_timens_data(vd);
vc = &vd->aux_clock_data[idx];
/* Re-read from the real time data page */
continue;
This 'continue' jumps to the end of the loop body and if the real vDSO datapage
by chance has a sequence counter of '1' will exit the loop, leaving 'sec' and
'nsec' uninitialized. My believe was that the 'continue' would jump to the
*beginning* of the loop body, which is cleary wrong. Previously there was an
inner while loop() which would make the 'continue' effectively start at the
beginning of the outer do-while loop.
}
/* Auxclock disabled? */
if (vc->clock_mode == VDSO_CLOCKMODE_NONE)
return false;
if (!vdso_get_timestamp(vd, vc, VDSO_BASE_AUX, &sec, &ns))
return false;
} while (vdso_read_retry(vc, seq));
vdso_set_timespec(ts, sec, ns);
I'm working on a fix.
Thomas
Le 22/04/2026 à 10:45, Thomas Weißschuh a écrit :
> On Wed, Apr 22, 2026 at 04:06:45PM +0800, Ricardo Ribalda wrote:
>> On Wed, 22 Apr 2026 at 15:32, Thomas Weißschuh
>> <thomas.weissschuh@linutronix.de> wrote:
>>>
>>> On Wed, Apr 22, 2026 at 03:00:11PM +0800, Ricardo Ribalda wrote:
>>>> On Wed, 22 Apr 2026 at 13:57, Thomas Weißschuh
>>>> <thomas.weissschuh@linutronix.de> wrote:
>>>>> On Wed, Apr 22, 2026 at 11:51:45AM +0800, Ricardo Ribalda wrote:
>>>>>> Media-CI has found a couple of new warnings in the latest kernel
>>>>>> version for aarch64 and powerpc. They get fixed with this patch and
>>>>>> before moving I wanted to know if this was under your radar.
>>>>>
>>>>> Thanks for the report. I was not aware of these so far.
>>>>>
>>>>>> diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
>>>>>> index 7dec05dd33b7..65914842fae0 100644
>>>>>> --- a/arch/arm64/kernel/vdso/Makefile
>>>>>> +++ b/arch/arm64/kernel/vdso/Makefile
>>>>>> @@ -50,7 +50,7 @@ CFLAGS_vgettimeofday.o = $(CC_FLAGS_ADD_VDSO)
>>>>>> CFLAGS_vgetrandom.o = $(CC_FLAGS_ADD_VDSO)
>>>>>>
>>>>>> ifneq ($(c-gettimeofday-y),)
>>>>>> - CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
>>>>>> + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
>>>>>> -Wno-maybe-uninitialized
>>>>>> endif
>>>>>
>>>>> (...)
>>>>>
>>>>> I'd like to know exactly what is going on before suppressing the warning.
>>>>> It is a non-standard warning, only enabled by *some* of the vDSO builds
>>>>> for some reason.
>>>>>
>>>>>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Flinux-media%2Fusers%2Fribalda%2F-%2Fpipelines%2F1649144%2Ftest_report%3Fjob_name%3Dcross-gcc&data=05%7C02%7Cchristophe.leroy2%40cs-soprasteria.com%7C7cbf9009269d4ddc16d208dea04b86f1%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639124443421115079%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=O4r8HjaUn7KEgW8tDE9GEC9e8CWyJBpCfhVTJZZ%2BFHs%3D&reserved=0
>>>>>
>>>>> While I was able to download a configuration from this job and also use the
>>>>> same container image, I can not reproduce the issue. Is the configuration the
>>>>> full one or only the template?
>>>>>
>>>>> Could you provide full reproduction steps?
>>>>
>>>> You can try repro with:
>>>>
>>>> work/linux $ podman run -v .:/workdir/ --rm -it
>>>> registry.freedesktop.org/linux-media/media-ci/build:latest
>>>> $ cd /workdir
>>>> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
>>>> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
>>>> arch/arm64/kernel/vdso/vgettimeofday.o
>>>>
>>>> The gcc version discrepancy is because I the error was due to old gcc
>>>> version and I was playing around with that... but it fails in both
>>>> gcc14 and gcc15
>>>
>>> Ack.
>>>
>>>> You can try with debian testing with
>>>> work/linux$ podman run -v .:/workdir/ --rm -it debian:testing
>>>> $ apt-get update
>>>> $ apt-get install gcc-aarch64-linux-gnu build-essential flex bison libssl-dev bc
>>>> $ cd /workdir
>>>> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make allyesconfig
>>>> $ CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
>>>> arch/arm64/kernel/vdso/vgettimeofday.o
>>>
>>> Both reproducers do *not* reproduce the issue for me.
>>> (It is more or less exactly what I tried before)
>>
>>
>> Ok, I think I found what is going on. media-ci was forcing
>> KCFLAGS=-Wmaybe-uninitialized
>>
>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Flinux-media%2Fmedia-ci%2F-%2Fblob%2Fmain%2Ftest-build.sh%3Fref_type%3Dheads%23L29&data=05%7C02%7Cchristophe.leroy2%40cs-soprasteria.com%7C7cbf9009269d4ddc16d208dea04b86f1%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C639124443421146576%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=%2FpTHYfCn5ob42%2Fm6FVOZ32PVzuXBNBT3rlMVWslCfhw%3D&reserved=0
>>
>> And something has changed in the kernel in the last version that
>> triggers a (hopefully) false positive.
>>
>> can you try with:
>>
>> CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
>> KCFLAGS=-Wmaybe-uninitialized allyesconfig
>> CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 make
>> KCFLAGS=-Wmaybe-uninitialized prepare
>
> That works!
>
> The warning was introduced in ed78b7b2c5ae ("vdso/gettimeofday: Add a helper to
> read the sequence lock of a time namespace aware clock").
>
> It is *not* a false-positive, specifically:
>
> do {
> if (vdso_read_begin_timens(vc, &seq)) {
> vd = __arch_get_vdso_u_timens_data(vd);
> vc = &vd->aux_clock_data[idx];
> /* Re-read from the real time data page */
> continue;
>
> This 'continue' jumps to the end of the loop body and if the real vDSO datapage
> by chance has a sequence counter of '1' will exit the loop, leaving 'sec' and
> 'nsec' uninitialized. My believe was that the 'continue' would jump to the
> *beginning* of the loop body, which is cleary wrong. Previously there was an
> inner while loop() which would make the 'continue' effectively start at the
> beginning of the outer do-while loop.
Well spotted. I missed it too while reviewing.
A 'retry:' label at the begining of the loop with a 'goto retry' instead
of the 'continue' should make it.
Christophe
>
> }
>
> /* Auxclock disabled? */
> if (vc->clock_mode == VDSO_CLOCKMODE_NONE)
> return false;
>
> if (!vdso_get_timestamp(vd, vc, VDSO_BASE_AUX, &sec, &ns))
> return false;
>
> } while (vdso_read_retry(vc, seq));
>
> vdso_set_timespec(ts, sec, ns);
>
>
> I'm working on a fix.
>
>
> Thomas
>
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