C Share a memory segment across jails

U

unitrunker

I've written code to share memory across processes but never thought to try this across jails. Is this supported?

Precisely - I'd like to create a shared memory segment in one jail but allow another process in another jail to map this segment into the other process's address space.
 

FreeBSD, Jails and SYSV IPC - TykBlog

Tyklings blog
blog.tyk.nu

Before FreeBSD 11 SYSV IPC resources were not namespaced, and you could only enable everything with allow.sysvipc=1 or enable nothing at all.
Click to expand...

In FreeBSD 11 allow.sysvipc=1 is no longer recommended, instead three new permissions has been introduced:
  • sysvshm: Controls access to shared memory
  • sysvsem: Controls access to SYSV semaphores
  • sysvmsg: Controls access to SYSV message queues
Each of these can have three values:
  • disable: Disables access to this type of resource (default)
  • inherit: Makes the jail inherit the global SYSV namespace (the old behaviour, same as allow.sysvipc=1)
  • new: Creates a new seperate SYSV namespace for this jail. This is what you want.
Click to expand...
I suspect this doesn't quite do what I want which is two or more jails share the same namespace for shared memory.
 
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