Messages in this thread | | | Date | Tue, 30 Mar 1999 22:23:34 +1000 | From | Richard Gooch <> | Subject | RE: Address spaces on a i386 - Getting Confused |
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Paul Sargent writes: > Ahhhh, so the kernel is always stored at physical address 0x00000000 > onwards, which is constantly mapped in at 0xC0000000 onwards. Therefore you > can get the physical address by lopping of the 0xC, but only on kernel > addresses.
Only on stuff returned from kmalloc() and get_free_page(), not for stuff returned from vmalloc() or ioremap(). The first two return addresses from the contiguous mapping of main RAM. The latter two return random virtual addresses.
> So presumably the other option is to allocate kernel memory and then > pass a pointer to it back to user space. Is that possible?
That's called mmap().
Regards,
Richard....
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