X86 bit in page table entry

Question

The Intel Architecture Guide says that when there is first access to write to a memory page, the CPU sets the dirty write bit in the page table. I have questions about this issue.

1. The 'dirty bit' in this context is used for guaranteeing the correctness of disk swapping in, out of memory pages. is this correct?
2. Is this automatically performed by the hardware? or is this an implementation of operating system?
3. If it is automatically performed by the hardware, is there any noteworthy difference compared to the usual memory updates which are performed by software instructions?

Thanks in advance.

Answer 1

1 "dirty bit" in this context is used to ensure the correct exchange of files on memory pages. it is right?

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