Re: JIT emulator needs
From: Albert Cahalan
Date: Sat Jun 09 2007 - 00:12:41 EST
On 6/8/07, Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote:
Albert Cahalan a écrit :
> Additions to better support JIT emulators:
> a. sysctl to set IPC_RMID by default
Not very good, this will break some apps.
As a sysctl, the admin gets to choose between
compatibility and sanity.
I can see such a sysctl also being really helpful for a
shared computer used for an Operating Systems or
System Programming course.
> b. shmget() flag to set IPC_RMID by default
This is better :)
Both are good. This one requires that all apps using
SysV shared memory be modified to use the flag.
The other requires that a very few apps be modified
to tolerate a behavior change.
> c. open() flag to unlink a file before returning the fd
Well, I assume you would like fd = open("/path/somefile", O_RDWR | O_CREAT |
(ie allocate a file handle but no name ?)
Quite difficult to implement this atomically with current vfs, maybe a new
syscall would be better. (Linus will kill me for that :) )
(We dont need to insert "somefile" in one directory, then unlink it, we only
need to allocate an unnamed inode to get some backing store)
I suspect that SMB/CIFS has a native call for this. There is
some sort of tmpfile flag defined over in that world.
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