Messages in this thread | | | Date | Sat, 17 Jul 1999 01:23:07 +0200 | From | Matthew Wilcox <> | Subject | Re: AGP & non-root mmap calls: "lending" priviledges to a client |
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On Fri, Jul 16, 1999 at 04:38:19PM -0600, Christopher Hassell wrote: > A question that has been presented to us is that of direct mmap() access to > AGP bridge-viewed RAM. For our AGP/GART device, the client non-root > processes that are coordinated by the X server are handed a "magic cookie" > that can be used to "bless" a device file descriptor (allowed inside the > kernel) ... and thus allow any mmap as needed directly from the AGP/GART > device. In general, then, only smart and X-server coordinated processes are > then able to do this, enhancing stability, but decreasing unneeded > centralization.
Will the SCM_RIGHTS ancillary message over unix domain sockets do what you want? See unix(7) for details (and if you don't have an entry for unix in section 7 of your manual pages, try the latest manpages package, available from ftp.win.tue.nl:/pub/linux-local/manpages or ftp.xx.kernel.org /pub/linux/docs/manpages).
With this message, the X server can pass an array of file descriptors to a client which can then call mmap on it.
-- Matthew Wilcox <willy@bofh.ai> "Windows and MacOS are products, contrived by engineers in the service of specific companies. Unix, by contrast, is not so much a product as it is a painstakingly compiled oral history of the hacker subculture." - N Stephenson
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