Hi...
1) Can the kernel access User Address Space.
Yes
If yes thats wat i found from
net ( but it is poorly written driver if it allows the same)
then why cant the kernel directly copy data from the user . Why do we need
copy_to_user and copy_from_user.
Is it because some protection mechanisms.
we need to make sure the user space address is valid. It means:
1. It is within valid user space address range (in 3:1 VM split, it's
0-3 GB)
2. It is within valid segment range (mentioned in related segment
descriptor)
regards,
Mulyadi
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