Shared data

[utzoo!decvax!ucbvax!unix-wizards]

>From cbosg!dale at Berkeley Tue Nov  3 00:22:04 1981
About a year and a half ago Alan Hewett in Columbus BTL implemented a
form of shared memory in UNIX which permitted a user process to attach
any segment of any regular UNIX file to it's address space. This was
done with complete locking built in: file segments could be attached
read, read/write, readonly, exclusive write, etc. Interlocking with
simultaneous "normal" read/write access was also provided. The hooks
necessary to support such a "feature" were extensive, and somewhat
ugly, however. It was implimented by actually mapping selected
system buffers into a user's precess space.