Hi All, why there is no character device entry present in /sys/class? where as block and net device entries are present. Not only in /sys/class, for that matter why there is no character device entries present in /sys file system. please help me to understand for what purpose char devices are kept away from /sys file system. Thanks Madhu
On Tue, May 23, 2017 at 11:58:31AM +0530, Madhu K wrote:
Hi All,
why there is no character device entry present in /sys/class? where as block and net device entries are present.
I see character devices there, but not the device nodes. I don't see block device nodes there either.
Not only in /sys/class, for that matter why there is no character device entries present in /sys file system.
What do you exactly mean by "character device entries"?
please help me to understand for what purpose char devices are kept away from / sys file system.
Have you read the driver model chapter in the Linux Device drivers book, or the in-kernel sysfs documentation? thanks, greg k-h
Hi Greg, Thanks for your response. On Tue, May 23, 2017 at 12:04 PM, Greg KH <greg@kroah.com> wrote:
On Tue, May 23, 2017 at 11:58:31AM +0530, Madhu K wrote:
Hi All,
why there is no character device entry present in /sys/class? where as block and net device entries are present.
I see character devices there, but not the device nodes. I don't see block device nodes there either.
If I am wrong please correct me, there is a folder called block in /sys/class. is block not containing block device nodes?
Not only in /sys/class, for that matter why there is no character device entries present in /sys file system.
What do you exactly mean by "character device entries"?
like block and net why there is no char folder
please help me to understand for what purpose char devices are kept away from / sys file system.
Have you read the driver model chapter in the Linux Device drivers book, or the in-kernel sysfs documentation?
thanks,
greg k-h
On Tue, May 23, 2017 at 12:58:07PM +0530, Madhu K wrote:
Hi Greg,
Thanks for your response.
On Tue, May 23, 2017 at 12:04 PM, Greg KH <greg@kroah.com> wrote:
On Tue, May 23, 2017 at 11:58:31AM +0530, Madhu K wrote: > Hi All, > > why there is no character device entry present in /sys/class? where as block > and net device entries are present.
I see character devices there, but not the device nodes. I don't see block device nodes there either.
If I am wrong please correct me, there is a folder called block in /sys/class. is block not containing block device nodes?
Nope, look closer :)
> Not only in /sys/class, for that matter why there is no character device > entries present in /sys file system.
What do you exactly mean by "character device entries"?
like block and net why there is no char folder
Again, look closer please.
> please help me to understand for what purpose char devices are kept away from / > sys file system.
Have you read the driver model chapter in the Linux Device drivers book, or the in-kernel sysfs documentation?
Again, please read all of the copious documentation that we have written already about this topic. If after that, you still have questions, I will be more than glad to help answer them. thanks, greg k-h
On Tue, May 23, 2017 at 2:53 PM, Greg KH <greg@kroah.com> wrote:
On Tue, May 23, 2017 at 12:58:07PM +0530, Madhu K wrote:
Hi Greg,
Thanks for your response.
On Tue, May 23, 2017 at 12:04 PM, Greg KH <greg@kroah.com> wrote:
On Tue, May 23, 2017 at 11:58:31AM +0530, Madhu K wrote: > Hi All, > > why there is no character device entry present in /sys/class? where as block > and net device entries are present.
I see character devices there, but not the device nodes. I don't see block device nodes there either.
If I am wrong please correct me, there is a folder called block in /sys/class. is block not containing block device nodes?
Nope, look closer :)
I checked the block folder, the entries which are present in /sys/class/block are softlink to /sys/devices nodes. what i understand from this is, all block net and char node entries are present in /sys/devices. Am i correct?
> Not only in /sys/class, for that matter why there is no character
device
> entries present in /sys file system.
What do you exactly mean by "character device entries"?
like block and net why there is no char folder
Again, look closer please.
> please help me to understand for what purpose char devices are
kept away
from / > sys file system.
Have you read the driver model chapter in the Linux Device drivers
book,
or the in-kernel sysfs documentation?
Again, please read all of the copious documentation that we have written already about this topic. If after that, you still have questions, I will be more than glad to help answer them.
thanks,
greg k-h
On Mon, May 29, 2017 at 10:58:09AM +0530, Madhu K wrote:
On Tue, May 23, 2017 at 2:53 PM, Greg KH <greg@kroah.com> wrote:
On Tue, May 23, 2017 at 12:58:07PM +0530, Madhu K wrote: > Hi Greg, > > Thanks for your response. > > > On Tue, May 23, 2017 at 12:04 PM, Greg KH <greg@kroah.com> wrote: > > On Tue, May 23, 2017 at 11:58:31AM +0530, Madhu K wrote: > > Hi All, > > > > why there is no character device entry present in /sys/class? where as > block > > and net device entries are present. > > I see character devices there, but not the device nodes. I don't see > block device nodes there either. > > > If I am wrong please correct me, there is a folder called block in /sys/ class. > is block not containing block device nodes?
Nope, look closer :)
I checked the block folder, the entries which are present in /sys/class/block are softlink to /sys/devices nodes.
What do you exactly mean by "nodes"? /sys/class/block/ points to the block device "class devices" in the kernel device hierarchy, just like the other /sys/class/* entries point to other class devices.
what i understand from this is, all block net and char node entries are present in /sys/devices. Am i correct?
Again, what do you mean by a "node"? Did you read the documentation about sysfs and the driver model? thanks, greg k-h
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