Messages in this thread | | | Subject | Re: AGP & non-root mmap calls: "lending" priviledges to a client | From | Andi Kleen <> | Date | 19 Jul 1999 16:21:48 +0200 |
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roell@xig.com (Thomas Roell) writes:
> In your message of 18 July 1999 you write: > > > > 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. > > > > > > Are there any plans to allow "handing over" priviledges to clients, from one > > > process to another? Should a technique of "trusted-cookies" be used to > > > > It already exists for general handle passing for file handles. > > Can you give me a pointer to that meachansim, and also how it's > handled in other Unix like operating systems ?
[for the Linux part] Get a copy of man-pages-1.24 and read unix(7)
SCM_CREDENTIALS is in newer BSD, but not in most other Unixes afaik. SCM_RIGHTS is available on most Unixes in slight variations. A good collection of fd passing functions ported to lots of systems is in the old NCSA httpd source.
-Andi
-- This is like TV. I don't like TV.
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