Is it called a “device driver” if it is not pointing to a hardware device?
The following diagram shows the relationship between a device file, a device driver, and a hardware device:
Application <---> /dev/device_file <---> device driver <---> hardware device
So the application writes data to the device file, and then the data gets passed to the device driver, and then the device driver passes the data to the hardware device (and the opposite happens when reading).
But there are device drivers in Linux that don't point to a hardware device, for example, the /dev/random device file points to a device driver that doesn't point to a hardware device:
Application <---> /dev/random <---> device driver
Is it accurate to say that /dev/random points to a "device driver", or is there another terminology to use?
linux terminology
asked Mar 7 at 22:22
user340660user340660
1
add a comment |
The following diagram shows the relationship between a device file, a device driver, and a hardware device:
Application <---> /dev/device_file <---> device driver <---> hardware device
So the application writes data to the device file, and then the data gets passed to the device driver, and then the device driver passes the data to the hardware device (and the opposite happens when reading).
But there are device drivers in Linux that don't point to a hardware device, for example, the /dev/random device file points to a device driver that doesn't point to a hardware device:
Application <---> /dev/random <---> device driver
Is it accurate to say that /dev/random points to a "device driver", or is there another terminology to use?
linux terminology
asked Mar 7 at 22:22
user340660user340660
1
These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41
add a comment |
The following diagram shows the relationship between a device file, a device driver, and a hardware device:
Application <---> /dev/device_file <---> device driver <---> hardware device
So the application writes data to the device file, and then the data gets passed to the device driver, and then the device driver passes the data to the hardware device (and the opposite happens when reading).
But there are device drivers in Linux that don't point to a hardware device, for example, the /dev/random device file points to a device driver that doesn't point to a hardware device:
Application <---> /dev/random <---> device driver
Is it accurate to say that /dev/random points to a "device driver", or is there another terminology to use?
linux terminology
asked Mar 7 at 22:22
user340660user340660
1
The following diagram shows the relationship between a device file, a device driver, and a hardware device:
Application <---> /dev/device_file <---> device driver <---> hardware device
So the application writes data to the device file, and then the data gets passed to the device driver, and then the device driver passes the data to the hardware device (and the opposite happens when reading).
But there are device drivers in Linux that don't point to a hardware device, for example, the /dev/random device file points to a device driver that doesn't point to a hardware device:
Application <---> /dev/random <---> device driver
Is it accurate to say that /dev/random points to a "device driver", or is there another terminology to use?
linux terminology
linux terminology
asked Mar 7 at 22:22
user340660user340660
1
asked Mar 7 at 22:22
user340660user340660
1
asked Mar 7 at 22:22
user340660user340660
1
asked Mar 7 at 22:22
user340660user340660
1
asked Mar 7 at 22:22
user340660user340660
1
1
These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41
add a comment |
These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41
These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41
add a comment |
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Your model is not correct. The dev files are provided by udev (or in older Linux's devfs). Now udev is apart of systemd. None of this is required at all, you can use drivers with direct API calls (like in Windows). In fact, afaik, some systems don't build with it.
Create a file in /dev is just a function of whatever created dev. Checkout mount | grep ' /dev '
udev on /dev type devtmpfs (rw,nosuid,relatime,size=8087376k,nr_inodes=2021844,mode=755)
^ See the udev. That's what created the abstraction.
The driver exists in the kernel. The abstraction layers is provided so you have file/io to the device. This follows the Unix methodology that all things are files, but it's not required.
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.getrandom()) but most don’t.
– Stephen Kitt
Mar 8 at 5:37
add a comment |
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Your model is not correct. The dev files are provided by udev (or in older Linux's devfs). Now udev is apart of systemd. None of this is required at all, you can use drivers with direct API calls (like in Windows). In fact, afaik, some systems don't build with it.
Create a file in /dev is just a function of whatever created dev. Checkout mount | grep ' /dev '
udev on /dev type devtmpfs (rw,nosuid,relatime,size=8087376k,nr_inodes=2021844,mode=755)
^ See the udev. That's what created the abstraction.
The driver exists in the kernel. The abstraction layers is provided so you have file/io to the device. This follows the Unix methodology that all things are files, but it's not required.
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.getrandom()) but most don’t.
– Stephen Kitt
Mar 8 at 5:37
add a comment |
Your model is not correct. The dev files are provided by udev (or in older Linux's devfs). Now udev is apart of systemd. None of this is required at all, you can use drivers with direct API calls (like in Windows). In fact, afaik, some systems don't build with it.
Create a file in /dev is just a function of whatever created dev. Checkout mount | grep ' /dev '
udev on /dev type devtmpfs (rw,nosuid,relatime,size=8087376k,nr_inodes=2021844,mode=755)
^ See the udev. That's what created the abstraction.
The driver exists in the kernel. The abstraction layers is provided so you have file/io to the device. This follows the Unix methodology that all things are files, but it's not required.
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.getrandom()) but most don’t.
– Stephen Kitt
Mar 8 at 5:37
add a comment |
Your model is not correct. The dev files are provided by udev (or in older Linux's devfs). Now udev is apart of systemd. None of this is required at all, you can use drivers with direct API calls (like in Windows). In fact, afaik, some systems don't build with it.
Create a file in /dev is just a function of whatever created dev. Checkout mount | grep ' /dev '
udev on /dev type devtmpfs (rw,nosuid,relatime,size=8087376k,nr_inodes=2021844,mode=755)
^ See the udev. That's what created the abstraction.
The driver exists in the kernel. The abstraction layers is provided so you have file/io to the device. This follows the Unix methodology that all things are files, but it's not required.
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
Your model is not correct. The dev files are provided by udev (or in older Linux's devfs). Now udev is apart of systemd. None of this is required at all, you can use drivers with direct API calls (like in Windows). In fact, afaik, some systems don't build with it.
Create a file in /dev is just a function of whatever created dev. Checkout mount | grep ' /dev '
udev on /dev type devtmpfs (rw,nosuid,relatime,size=8087376k,nr_inodes=2021844,mode=755)
^ See the udev. That's what created the abstraction.
The driver exists in the kernel. The abstraction layers is provided so you have file/io to the device. This follows the Unix methodology that all things are files, but it's not required.
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
edited Mar 8 at 0:17
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
answered Mar 8 at 0:11
Evan CarrollEvan Carroll
6,055114586
6,055114586
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.getrandom()) but most don’t.
– Stephen Kitt
Mar 8 at 5:37
add a comment |
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.getrandom()) but most don’t.
– Stephen Kitt
Mar 8 at 5:37
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.
getrandom()) but most don’t.– Stephen Kitt
Mar 8 at 5:37
Device nodes are part of the kernel API, they’re not an external abstraction. Some drivers have equivalent system calls (e.g.
getrandom()) but most don’t.– Stephen Kitt
Mar 8 at 5:37
add a comment |
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These are called pseudo-devices on some systems.
– Kusalananda♦
Mar 7 at 22:25
When you read/write/ioctl the device file, you're calling into the driver program, which might operate the read hardware or calling some internal non-hardware-related kernel function. The device node itself is simply an interface that kernel expose to you.
– 炸鱼薯条德里克
Mar 8 at 0:41