temporarily disabling udev

temporarily disabling udev

[Marco d'Itri]

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I need to patch udev to be sure that it will not modify /dev if
udevstart has been not been run (e.g. because root disabled the
init script, or it failed for some reason).
Would this work?

diff -ruNp udev-048.orig/udev.c udev-048/udev.c
--- udev-048.orig/udev.c	2004-12-08 20:43:16.000000000 +0100
+++ udev-048/udev.c	2004-12-19 15:09:51.000000000 +0100
@@ -83,6 +83,15 @@ exit:
 	return 0;
 }
 
+/* return true if the udev database exists */
+static int udev_active(void) {
+	struct stat stats;
+
+	if (stat (udev_db_path, &stats) == 0)
+		return 1;
+	return 0;
+}
+
 static void asmlinkage sig_handler(int signum)
 {
 	switch (signum) {
@@ -161,6 +170,9 @@ int main(int argc, char *argv[], char *e
 	if (udev_log)
 		setenv("UDEV_LOG", "1", 1);
 
+	if (!udev_active())
+		goto hotplug;
+
 	if ((strncmp(devpath, "/block/", 7) == 0) || (strncmp(devpath, "/class/", 7) == 0)) {
 		if (strcmp(action, "add") == 0) {
 			/* wait for sysfs and possibly add node */


-- 
ciao, |
Marco | [9919 peXnx6UiWKdTk]

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Re: temporarily disabling udev

[Kay Sievers]

On Sun, 2004-12-19 at 15:56 +0100, Marco d'Itri wrote:
> I need to patch udev to be sure that it will not modify /dev if
> udevstart has been not been run (e.g. because root disabled the
> init script, or it failed for some reason).
> Would this work?

Removing the database, should not prevent the next udev run to create
one. udev is used in initrd with /proc/sys/kernel/hotplug set
to /sbin/udev in some setups, which will not work with this patch.

How does Debian disable udev? Can't you use this value instead?

Kay



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Re: temporarily disabling udev

[Marco d'Itri]

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On Dec 19, Kay Sievers <kay.sievers@vrfy.org> wrote:

> > I need to patch udev to be sure that it will not modify /dev if
> > udevstart has been not been run (e.g. because root disabled the
> > init script, or it failed for some reason).
> > Would this work?
> Removing the database, should not prevent the next udev run to create
> one.
Do you have other suggestions?

> udev is used in initrd with /proc/sys/kernel/hotplug set
> to /sbin/udev in some setups, which will not work with this patch.
Why they do not run udevstart?

> How does Debian disable udev? Can't you use this value instead?
The standard method to disable a daemon is to disable its init script.

-- 
ciao, |
Marco | [9920 alZroOc39eF8Y]

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Re: temporarily disabling udev

[Kay Sievers]

On Sun, 2004-12-19 at 16:43 +0100, Marco d'Itri wrote:
> On Dec 19, Kay Sievers <kay.sievers@vrfy.org> wrote:
> 
> > > I need to patch udev to be sure that it will not modify /dev if
> > > udevstart has been not been run (e.g. because root disabled the
> > > init script, or it failed for some reason).
> > > Would this work?
> > Removing the database, should not prevent the next udev run to create
> > one.
> Do you have other suggestions?

No, not really. I just see problems with the patch in the upstream
version, cause of the numerous setups udev is used.

> > udev is used in initrd with /proc/sys/kernel/hotplug set
> > to /sbin/udev in some setups, which will not work with this patch.
> Why they do not run udevstart?

They want to use the device nodes after module load. At the time
udevstart would run, there may not all modules be loaded.

Kay



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Re: temporarily disabling udev

[Marco d'Itri]

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On Dec 19, Kay Sievers <kay.sievers@vrfy.org> wrote:

> No, not really. I just see problems with the patch in the upstream
> version, cause of the numerous setups udev is used.
For the time being then I will keep it a debian-specific patch...

> > > udev is used in initrd with /proc/sys/kernel/hotplug set
> > > to /sbin/udev in some setups, which will not work with this patch.
> > Why they do not run udevstart?
> They want to use the device nodes after module load. At the time
> udevstart would run, there may not all modules be loaded.
I mean, what stops them from running udevstart before starting to load
modules?

-- 
ciao, |
Marco | [9923 soplLOhA2XZzc]

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