Date: Wed, 8 Nov 1995 07:49:00 +0000 () From: Michael Smith <msmith@atrad.adelaide.edu.au> To: hackers@freebsd.org Subject: ioctl() question... Message-ID: <199511080749.HAA06456@genesis.atrad.adelaide.edu.au>
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A device-driver level question :
I have some ioctls :
struct buf
{
u_short count, timeout, status;
u_short data[256];
}
#define GETSTUFF _IOR('p', 15, struct buf)
#define PUTSTUFF _IOW('p', 16, struct buf)
#define PUTSTATUS _IOR('p', 17, int)
Where PUTSTATUS gets the status of the last put operation. This is
yucko and non-orthagonal, and I'd prefer to do
#define PUTSTUFF _IOWR('p', 16, struct buf)
but I'm ignorant of the relative merits wrt copyin/copyout time vs.
syscall time.
It's also possible that the data[] array may grow, although I'm trading
off against read/write with that 8(
--
]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[
]] Genesis Software genesis@atrad.adelaide.edu.au [[
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