kernel modules and 64-bit kernels

[posted this query on [email protected] earlier]

Hello,

Do kernel modules need to be aware that they are running in a 64-bit kernel or a 32-bit kernel?

I guess yes, especially interacting with 32-bit userspace programs. For e.g. if a 32-bit program (running on a 64-bit kernel) passes a pointer to the kernel module (via an ioctl), how does the kernel/module know that its a 32-bit address? the sizeof(pointer) changes in kernel/userspace in this case. So in the ioctl handler the kernel modules does how many bytes of copy_from_use() to get the ioctl args?

How should be the modules be written so they work both on 32/64-bit kernel AND can interact with both 32/64-bit userspace programs in a 64-bit kernel??

Any links, pointers to relevant HOWTO/docs/source will be very useful.

Thanks,
A.

ps: Please Cc: me the reply. I am not on this mailing list.

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