Messages in this thread |  | | Subject | Re: [Regression] Missing device nodes for ETR, ETF and STM after CONFIG_UEVENT_HELPER=n | From | Sai Prakash Ranjan <> | Date | Fri, 26 Jul 2019 15:44:40 +0530 |
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On 7/26/2019 3:14 PM, Sai Prakash Ranjan wrote: > On 7/26/2019 2:11 PM, Greg Kroah-Hartman wrote: >> On Fri, Jul 26, 2019 at 01:50:27PM +0530, Sai Prakash Ranjan wrote: >>> On 7/26/2019 12:34 PM, Greg Kroah-Hartman wrote: >>>> On Fri, Jul 26, 2019 at 11:49:19AM +0530, Sai Prakash Ranjan wrote: >>>>> Hi, >>>>> >>>>> When trying to test my coresight patches, I found that etr,etf and stm >>>>> device nodes are missing from /dev. >>>> >>>> I have no idea what those device nodes are. >>>> >>>>> Bisection gives this as the bad commit. >>>>> >>>>> 1be01d4a57142ded23bdb9e0c8d9369e693b26cc is the first bad commit >>>>> commit 1be01d4a57142ded23bdb9e0c8d9369e693b26cc >>>>> Author: Geert Uytterhoeven <geert+renesas@glider.be> >>>>> Date: Thu Mar 14 12:13:50 2019 +0100 >>>>> >>>>> driver: base: Disable CONFIG_UEVENT_HELPER by default >>>>> >>>>> Since commit 7934779a69f1184f ("Driver-Core: disable >>>>> /sbin/hotplug by >>>>> default"), the help text for the /sbin/hotplug fork-bomb says >>>>> "This should not be used today [...] creates a high system >>>>> load, or >>>>> [...] out-of-memory situations during bootup". The rationale >>>>> for this >>>>> was that no recent mainstream system used this anymore (in >>>>> 2010!). >>>>> >>>>> A few years later, the complete uevent helper support was >>>>> made optional >>>>> in commit 86d56134f1b67d0c ("kobject: Make support for >>>>> uevent_helper >>>>> optional."). However, if was still left enabled by default, >>>>> to support >>>>> ancient userland. >>>>> >>>>> Time passed by, and nothing should use this anymore, so it >>>>> can be >>>>> disabled by default. >>>>> >>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> >>>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>>>> >>>>> drivers/base/Kconfig | 1 - >>>>> 1 file changed, 1 deletion(-) >>>>> >>>>> >>>>> Any idea on this? >>>> >>>> That means that who ever created those device nodes is relying on udev >>>> to do this, and is not doing the correct thing within the kernel and >>>> using devtmpfs. >>>> >>>> Any pointers to where in the kernel those devices are trying to be >>>> created? >>>> >>> >>> Somewhere in drivers/hwtracing/coresight/* probably. I am not sure, >>> Mathieu/Suzuki would be able to point you to the exact code. >>> >>> Also just to add on some more details, I am using *initramfs* >> >> Are you using devtmpfs for your /dev/ mount? >> > > I am not mounting devtmpfs. However > > CONFIG_DEVTMPFS=y > CONFIG_DEVTMPFS_MOUNT=y >
Ok my initramfs is using mdev:
*/sbin/mdev -s*
This somehow is not mounting etr, etf, stm devices when uevent-helper is disabled. Anyways as Suzuki mentioned, using devtmpfs does fix the issue.
Thanks, Sai
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