kernel rakshakudu wrote:
>
> thanks joe,
> but is there any reason why linux selected flat model
> for segmentation.
Portability: not all architectures have segmentation.
On those that do, it often works in very different
ways (Well, that's an unsupported assertion: I know of
no other modern architecture with segmentation,
though I'm sure they're out there. But the
Intel segmentation model doesn't seem to me to be
motivated by any strong general principles, and
therefore I assume there's no particular reason any
other segmentation model should resemble Intel's).
Trying to implement a segmentation abstraction
that worked uniformly across all platforms (including
those with no segmentation) would be very difficult.
Simplicity: The segmentation model chosen by Intel is
particularly complicated and unwieldy; ignoring it
simplifies the kernel code considerably.
Occam's Razor: Page-level protection achieves, in a
portable way, the protection that you get with
segmentation. Why impose the burden of segment
management for little or no benefit?
Cheers,
-- Joe
"Thanks to Microsoft, I am now blind in both eyes. They have
rolled back in my head so many times this week that they
are apparently stuck there now."
- Jonathan Rickman, regarding M$ anti-open-source PR.
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
