Date: Mon, 18 Aug 1997 11:25:11 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: marc@bowtie.nl Cc: emulation@FreeBSD.ORG Subject: Re: semget in linux emulation? Message-ID: <199708180155.LAA08632@genesis.atrad.adelaide.edu.au> In-Reply-To: <199708050922.LAA04626@nietzsche.bowtie.nl> from Marc van Kempen at "Aug 5, 97 11:22:13 am"
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Ooh, old mail 8)
Marc van Kempen stands accused of saying:
>
> I have a Linux application that I want to run on a
> 2.2.2 system, but it seems to use shared memory.
> I config'ed shared memory in my kernel.
>
> The application complains about a failing SEMGET,
> and when I looked in the linux_ipc.c, the call returns
> ENOSYS, does this mean that the semget won't work????
Yes.
> If so, is anyone working on fixing this? Or, how difficult
> is it to add?
I don't believe so. Adding it basically just involves writing a shim
that translates the Linux system call arguments/return to/from the BSD
syscall arguments. It should be pretty straightforward, once you work
out what the Linux code actually wants.
Grr. Looking at the Linux section-2 manpages, they lay their shared-memory
region out differently from ours. Theirs looks like :
struct shmid_ds {
struct ipc_perm shm_perm; /* operation perms */
int shm_segsz; /* size of segment (bytes) */
time_t shm_atime; /* last attach time */
time_t shm_dtime; /* last detach time */
time_t shm_ctime; /* last change time */
unsigned short shm_cpid; /* pid of creator */
unsigned short shm_lpid; /* pid of last operator */
short shm_nattch; /* no. of current attaches */
/* the following are private */
unsigned short shm_npages; /* size of segment (pages) */
unsigned long *shm_pages; /* array of ptrs to frames -> SHMMAX */
struct vm_area_struct *attaches; /* descriptors for attaches */
};
And ours is :
/*
* As defined+described in "X/Open System Interfaces and Headers"
* Issue 4, p. XXX
*/
struct shmid_ds {
struct ipc_perm shm_perm; /* operation permission structure */
int shm_segsz; /* size of segment in bytes */
pid_t shm_lpid; /* process ID of last shared memory op */
pid_t shm_cpid; /* process ID of creator */
short shm_nattch; /* number of current attaches */
time_t shm_atime; /* time of last shmat() */
time_t shm_dtime; /* time of last shmdt() */
time_t shm_ctime; /* time of last change by shmctl() */
void *shm_internal; /* sysv stupidity */
};
This might be moderately tricky; you would have to identify whether the
segment was created Linux-style or BSD-style and handle it accordingly.
> Marc van Kempen BowTie Technology
--
]] Mike Smith, Software Engineer msmith@gsoft.com.au [[
]] Genesis Software genesis@gsoft.com.au [[
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