Linux virtual subsystem

[div123]

Hi, I am trying to implement a mmap system call, so I went through the linux virtual memory subsystem concepts.
I got to know about the 1GB kernel space and 3GB user space concept, but I am unable to correlate it with the physical memory available in the system.
Any help will be highly appreciated.

[gerard4143]

I got to know about the 1GB kernel space and 3GB user space concept, but I am unable to correlate it with the physical memory available in the system

What are you having problems understanding...is it page tables an how they relate to physical memory and system resources or is it the concept of virtual memory altogether? Or are you having problems with user/kernel space?

I ask because you really don't need to know the details to implement mmap system call but if your interested there is plenty of web sites catering to these topics plus of course Linux Forums...Gerard4143

[div123]

Thanks for replying so fast.
The problem is that i am unable to correlate the concept of virtual memory subsystem to the PC and furthur to the embedded system which is having much less physical memory at disposal.
For example, I have a 1GB physical memory(RAM); now, where does the kernel and user space reside in accordance to (1GB/3GB) concept.

[gerard4143]

Here's a good starting point for understand virtual memory...it will at least introduce you to some of the terms...Hope this helps Gerard4143

Explore the Linux memory model

[div123]

Thanks for the pointer to a good resource.