在单用户模式下从linux内核共享内存到用户空间

Question

I have a kernel module that allocates memory and I would like to share this memory with a user process. In normal mode we can only do that with: mmap, /proc, shmem, etc. but in single user mode, for embedded devices, isn't there a way to share a simple pointer?

Answer 1

"Single user mode" is a convention defined by userspace. It has no significance to the kernel; all of the same rules apply as "normal mode".

If you want to access memory -- any memory -- from userspace, you will need to map that memory into the process somehow. Using mmap() on a special file or device node is the most natural way of doing this.

Answer 2

The pseudo sysfs file system ( /sys ) was intended for this very purpose (expose kernel data to userspace). You may also write to these data structures from user space.

Check out Greg Kroah-Hartman's Driver Tutorial

Read SysFS Documentation