* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
@ 2019-05-23 13:14 Andy Shevchenko
2019-05-23 14:33 ` Peter Korsgaard
0 siblings, 1 reply; 6+ messages in thread
From: Andy Shevchenko @ 2019-05-23 13:14 UTC (permalink / raw)
To: buildroot
At runtime on most of the modern kernels [1] S10mdev script produces an error:
/etc/init.d/S10mdev: line 9: can't create /proc/sys/kernel/hotplug: nonexistent directory
since the commit
caae7fa1d737 ("busybox: register mdev as hotplug helper when selected")
added it unconditionally.
Check the presence of procfs node before writing to it.
[1]: Linux kernels with the commit
86d56134f1b6 ("kobject: Make support for uevent_helper optional.")
applied.
Fixes: caae7fa1d737 ("busybox: register mdev as hotplug helper when selected")
Cc: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
package/busybox/S10mdev | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/package/busybox/S10mdev b/package/busybox/S10mdev
index 7075b77016..ddede9a4a6 100644
--- a/package/busybox/S10mdev
+++ b/package/busybox/S10mdev
@@ -6,7 +6,7 @@
case "$1" in
start)
echo "Starting mdev..."
- echo /sbin/mdev >/proc/sys/kernel/hotplug
+ test -f /proc/sys/kernel/hotplug && echo /sbin/mdev > /proc/sys/kernel/hotplug
/sbin/mdev -s
# coldplug modules
find /sys/ -name modalias -print0 | xargs -0 sort -u | tr '\n' '\0' | \
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
2019-05-23 13:14 [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error Andy Shevchenko
@ 2019-05-23 14:33 ` Peter Korsgaard
2019-05-24 7:49 ` Peter Korsgaard
0 siblings, 1 reply; 6+ messages in thread
From: Peter Korsgaard @ 2019-05-23 14:33 UTC (permalink / raw)
To: buildroot
>>>>> "Andy" == Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> At runtime on most of the modern kernels [1] S10mdev script produces an error:
> /etc/init.d/S10mdev: line 9: can't create /proc/sys/kernel/hotplug: nonexistent directory
> since the commit
> caae7fa1d737 ("busybox: register mdev as hotplug helper when selected")
> added it unconditionally.
> Check the presence of procfs node before writing to it.
> [1]: Linux kernels with the commit
> 86d56134f1b6 ("kobject: Make support for uevent_helper optional.")
> applied.
But how can mdev work on such setups?
--
Bye, Peter Korsgaard
^ permalink raw reply [flat|nested] 6+ messages in thread* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
2019-05-23 14:33 ` Peter Korsgaard
@ 2019-05-24 7:49 ` Peter Korsgaard
2019-05-24 13:25 ` Andy Shevchenko
0 siblings, 1 reply; 6+ messages in thread
From: Peter Korsgaard @ 2019-05-24 7:49 UTC (permalink / raw)
To: buildroot
>>>>> "Peter" == Peter Korsgaard <peter@korsgaard.com> writes:
>>>>> "Andy" == Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
>> At runtime on most of the modern kernels [1] S10mdev script produces an error:
>> /etc/init.d/S10mdev: line 9: can't create /proc/sys/kernel/hotplug: nonexistent directory
>> since the commit
>> caae7fa1d737 ("busybox: register mdev as hotplug helper when selected")
>> added it unconditionally.
>> Check the presence of procfs node before writing to it.
>> [1]: Linux kernels with the commit
>> 86d56134f1b6 ("kobject: Make support for uevent_helper optional.")
>> applied.
> But how can mdev work on such setups?
To be clear, if mdev needs CONFIG_UEVENT_HELPER=y for hotplug
notifications, then we should rather force that in linux/linux.mk and
mention the dependency in the mdev help text rather than silently not
having hotplug work.
I have marked this patch as changes requested in patchwork.
--
Bye, Peter Korsgaard
^ permalink raw reply [flat|nested] 6+ messages in thread* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
2019-05-24 7:49 ` Peter Korsgaard
@ 2019-05-24 13:25 ` Andy Shevchenko
2019-05-24 21:12 ` Peter Korsgaard
0 siblings, 1 reply; 6+ messages in thread
From: Andy Shevchenko @ 2019-05-24 13:25 UTC (permalink / raw)
To: buildroot
On Fri, May 24, 2019 at 09:49:30AM +0200, Peter Korsgaard wrote:
> >>>>> "Peter" == Peter Korsgaard <peter@korsgaard.com> writes:
>
> >>>>> "Andy" == Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> >> At runtime on most of the modern kernels [1] S10mdev script produces an error:
> >> /etc/init.d/S10mdev: line 9: can't create /proc/sys/kernel/hotplug: nonexistent directory
>
> >> since the commit
>
> >> caae7fa1d737 ("busybox: register mdev as hotplug helper when selected")
>
> >> added it unconditionally.
>
> >> Check the presence of procfs node before writing to it.
>
> >> [1]: Linux kernels with the commit
> >> 86d56134f1b6 ("kobject: Make support for uevent_helper optional.")
> >> applied.
>
> > But how can mdev work on such setups?
At least the script is used to initialize modules at the boot time.
What happens afterwards I didn't investigate. I have no such issues.
> To be clear, if mdev needs CONFIG_UEVENT_HELPER=y for hotplug
> notifications, then we should rather force that in linux/linux.mk and
> mention the dependency in the mdev help text rather than silently not
> having hotplug work.
>
> I have marked this patch as changes requested in patchwork.
Kernel can be built outside of Buildroot. Still this needs to be fixed.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 6+ messages in thread* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
2019-05-24 13:25 ` Andy Shevchenko
@ 2019-05-24 21:12 ` Peter Korsgaard
2019-05-24 21:39 ` Andy Shevchenko
0 siblings, 1 reply; 6+ messages in thread
From: Peter Korsgaard @ 2019-05-24 21:12 UTC (permalink / raw)
To: buildroot
>>>>> "Andy" == Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
>> > But how can mdev work on such setups?
> At least the script is used to initialize modules at the boot time.
> What happens afterwards I didn't investigate. I have no such issues.
You mean the:
# coldplug modules
find /sys/ -name modalias -print0 | xargs -0 sort -u | tr '\n' '\0' | \
xargs -0 modprobe -abq
That indeed does not depend on mdev working.
>> To be clear, if mdev needs CONFIG_UEVENT_HELPER=y for hotplug
>> notifications, then we should rather force that in linux/linux.mk and
>> mention the dependency in the mdev help text rather than silently not
>> having hotplug work.
>>
>> I have marked this patch as changes requested in patchwork.
> Kernel can be built outside of Buildroot. Still this needs to be fixed.
And just like all other packages that require specific kernel options
enabled, if you are not using Buildroot to build the kernel then you
have to ensure the kernel has the right config options enabled.
I am not sure what you mean exactly with "Still this needs to be
fixed". The only fix I can think of is what I mentioned above,
E.G. document the need for CONFIG_UEVENT_HELPER in the help text and
automatically enable it in linux.mk.
Expecting mdev to work sensible on a system without uevent helper
support isn't sensible, it is similar to having radvd (IPv6 router
advertising daemon) work on a system without IPv6.
--
Bye, Peter Korsgaard
^ permalink raw reply [flat|nested] 6+ messages in thread* [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error
2019-05-24 21:12 ` Peter Korsgaard
@ 2019-05-24 21:39 ` Andy Shevchenko
0 siblings, 0 replies; 6+ messages in thread
From: Andy Shevchenko @ 2019-05-24 21:39 UTC (permalink / raw)
To: buildroot
On Fri, May 24, 2019 at 11:12:17PM +0200, Peter Korsgaard wrote:
> >>>>> "Andy" == Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
>
> >> > But how can mdev work on such setups?
>
> > At least the script is used to initialize modules at the boot time.
> > What happens afterwards I didn't investigate. I have no such issues.
>
> You mean the:
>
> # coldplug modules
> find /sys/ -name modalias -print0 | xargs -0 sort -u | tr '\n' '\0' | \
> xargs -0 modprobe -abq
>
> That indeed does not depend on mdev working.
>
>
> >> To be clear, if mdev needs CONFIG_UEVENT_HELPER=y for hotplug
> >> notifications, then we should rather force that in linux/linux.mk and
> >> mention the dependency in the mdev help text rather than silently not
> >> having hotplug work.
> >>
> >> I have marked this patch as changes requested in patchwork.
>
> > Kernel can be built outside of Buildroot. Still this needs to be fixed.
>
> And just like all other packages that require specific kernel options
> enabled, if you are not using Buildroot to build the kernel then you
> have to ensure the kernel has the right config options enabled.
>
> I am not sure what you mean exactly with "Still this needs to be
> fixed". The only fix I can think of is what I mentioned above,
> E.G. document the need for CONFIG_UEVENT_HELPER in the help text and
> automatically enable it in linux.mk.
>
> Expecting mdev to work sensible on a system without uevent helper
> support isn't sensible, it is similar to having radvd (IPv6 router
> advertising daemon) work on a system without IPv6.
I'm not sure if mdev follows the change in the kernel, but uEvent helper is
obsolete mechanism.
--- 8< --- 8< --- 8< ---
The external binary /sbin/hotplug was used in earlier releases to inform Udev
about device state change. That has been replaced and Udev can now directly
listen to those events through Netlink.
--- 8< --- 8< --- 8< ---
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-05-24 21:39 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2019-05-23 13:14 [Buildroot] [PATCH v1] package/busybox: Avoid "can't create /proc/sys/kernel/hotplug" error Andy Shevchenko
2019-05-23 14:33 ` Peter Korsgaard
2019-05-24 7:49 ` Peter Korsgaard
2019-05-24 13:25 ` Andy Shevchenko
2019-05-24 21:12 ` Peter Korsgaard
2019-05-24 21:39 ` Andy Shevchenko
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.