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    SubjectRe: Differences between FreeBSD and Linux system call mechanism
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    In message <m0zEZjD-000aPLC@the-village.bc.nu>, Alan Cox writes:
    +-----
    | > > required. The FreeBSD mechanism for kernel entry (and subsequet
    | > > context switch) is threfore more efficient than that used by Linux.
    | > 1) Linux system calls are done using software interrupt 0x80 on ia32.
    | > Does this qualify as a "call-gate based kernel entry"?
    |
    | No. Call gates are a paticular intel mechanism for jumping between rings
    | (priviledge levels). You can see an example of this in the iBCS2 handlers
    | since iBCS uses call gates. An int based call is faster, and sysenter
    | is potentially faster still but sysenter is only on some later PII chips
    +--->8

    The odd thing is that iBCS still contains remnants of an attempt at xBSD
    emulation, predicated on xBSD using the same call gate as iBCS (lcall 7,0).
    Did xBSD switch to something else at some point, or was Terry talking
    completely out of his hat about Linux vs. xBSD and call gates?

    --
    brandon s. allbery [os/2][linux][solaris][japh] allbery@kf8nh.apk.net
    system administrator [WAY too many hats] allbery@ece.cmu.edu
    electrical and computer engineering KF8NH
    carnegie mellon university



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