Date: Thu, 15 Aug 2002 17:25:12 +0800 From: "ouyang kai" <oykai@msn.com> To: "Lambert Terry" <tlambert2@mindspring.com>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: About 'sysctl' routine problem? Message-ID: <OE173Kegmprho5fimNY000222e7@hotmail.com>
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Dear Terry,
Thank you!
>Once again, we are talking about linker sets. This is a little
>more complex, though, since you have to take the "boot environment"
>into account, as well (the boot environment is the basis for a
>preinitialized sysctl space contents, seperate from the code you
>see in the kernel itself for the declarations of specific sysctl
>OIDs that are added to the ones exported before the kernel is even
>really started.
in kern_mib.c:
SYSCTL_NODE(, CTL_NET, net, CTLFLAG_RW, 0,
"Network, (see socket.h)");
-->
struct sysctl_oid_list sysctl_net_children;
static struct sysctl_oid sysctl__net = {
&sysctl_children, { 0 },
CTL_NET, CTLTYPE_NODE|CTLFLAG_RW, (void*)&sysctl_net_children,
0, "net", 0, "N", 0 };
DATA_SET(sysctl_set, sysctl__net);
It seem like the SYSINIT macro.
> TUNABLE_INT_DECL
> TUNABLE_INT_FETCH
> SYSCTL_DECL
> SYSCTL_NODE
> SYSCTL_INT
> SYSCTL_STRUCT
> SYSCTL_PROC
Whether do they register also in mi_startup() like other devices, when the
'sipp' is looped to 'SI_SUB_TUNABLES'?
You said some specific sysctl OIDs can be added before the kernel is even really started,
I want to know when they will be added? Could you give me an example?
I try to trace some routine from the 'ifconfig' program source code.
The following code is copied from 'ifconfig' program:
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = 0; /* address family */
mib[4] = NET_RT_IFLIST;
mib[5] = 0;
/* if particular family specified, only ask about it */
if (afp)
mib[3] = afp->af_af;
if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
errx(1, "iflist-sysctl-estimate");
From the SYSCTL_NODE(_net, PF_ROUTE, routetable, CTLFLAG_RD, sysctl_rtsock, "");
we can know the RF_ROUTE is the 'net's children', and its' handler is sysctl_rtsock.
So, the kernel will call sysctl_rtsock, right?
in sysctl_rtsock function:
case NET_RT_IFLIST:
error = sysctl_iflist(af, &w);
So, this time, the kernel will call sysctl_iflist finally, right?
But I have some wonder how the 'sysctl' command transfer from user space to kernel space?
I find the line in sysproto.h:
int __sysctl __P((struct proc *, struct sysctl_args *));
I think whether the 'sysctl' is changed to '__sysctl' in kernel space?
If that is right, the __sysctl is how conect with sysctl_rtsock?
Thank you very much!:-)
Best Regards
Ouyang Kai
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