(userspace) vfs and xio

ibotty bsd at ibotty.net
Thu May 20 10:50:59 PDT 2004

Matt and others,

first some basic Q:
can a xio_t be used in userland (as it can hold userspace data),
can a process (possibly with root credentials) read or write to xio_t pages
of another process? if not (i assume so), is there a possibility to allow
that (maybe as fbufs [1] or to mmap)?

now to the vfs:
Matt, you plan(ned) to convert most io w/ uio to xio. does that include vfs?
i think so, but it does collide with your vfs model plans [2] ("The VOP
interface will NOT handle direct userspace addresses any more"). i guess
the xio abstraction is enough, but maybe you still think, pages should be
copied to kvm before...
will the new vop api be similar to the old one (except uio stuff of course)?

and finally, may there be filesystem processes (fileservers as in plan9),
that have no root-euid, i hope so :)


[1] http://www.cs.binghamton.edu/~ghose/CS529/fbufs.pdf
[2] http://www.dragonflybsd.org/goals/vfsmodel.cgi

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