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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jul 26, 2019 at 03:44:40PM +0530, Sai Prakash Ranjan wrote: > 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 wrot= e: > > > > > > 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 > > > > > > Date:=A0=A0 Thu Mar 14 12:13:50 2019 +0100 > > > > > > = > > > > > > =A0=A0=A0=A0=A0 driver: base: Disable CONFIG_UEVENT_HELPER by d= efault > > > > > > = > > > > > > =A0=A0=A0=A0=A0 Since commit 7934779a69f1184f ("Driver-Core: > > > > > > disable /sbin/hotplug by > > > > > > =A0=A0=A0=A0=A0 default"), the help text for the /sbin/hotplug = fork-bomb says > > > > > > =A0=A0=A0=A0=A0 "This should not be used today [...] creates a > > > > > > high system load, or > > > > > > =A0=A0=A0=A0=A0 [...] out-of-memory situations during bootup".= =A0 > > > > > > The rationale for this > > > > > > =A0=A0=A0=A0=A0 was that no recent mainstream system used this > > > > > > anymore (in 2010!). > > > > > > = > > > > > > =A0=A0=A0=A0=A0 A few years later, the complete uevent helper > > > > > > support was made optional > > > > > > =A0=A0=A0=A0=A0 in commit 86d56134f1b67d0c ("kobject: Make supp= ort > > > > > > for uevent_helper > > > > > > =A0=A0=A0=A0=A0 optional.").=A0 However, if was still left enab= led > > > > > > by default, to support > > > > > > =A0=A0=A0=A0=A0 ancient userland. > > > > > > = > > > > > > =A0=A0=A0=A0=A0 Time passed by, and nothing should use this > > > > > > anymore, so it can be > > > > > > =A0=A0=A0=A0=A0 disabled by default. > > > > > > = > > > > > > =A0=A0=A0=A0=A0 Signed-off-by: Geert Uytterhoeven > > > > > > =A0=A0=A0=A0=A0 Signed-off-by: Greg Kroah-Hartman > > > > > > = > > > > > > =A0=A0 drivers/base/Kconfig | 1 - > > > > > > =A0=A0 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 > > = > > =A0CONFIG_DEVTMPFS=3Dy > > =A0CONFIG_DEVTMPFS_MOUNT=3Dy > > = > = > 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. Last I looked (many years ago) mdev requires uevent-helper in order for it to work. I recommend that if you rely on mdev to keep that option enabled, or to just use devtmpfs and udev :) thanks, greg k-h _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel