"Handbook / Chapter 19 GEOM" question

[Sergey Kandaurov]

2011/2/24 Pavel Sukhoy <sukhoy at nic.ru>:
> Hello all,
>
> Could you tell me some clarifications about section "19.4.1 Mirroring Primary Disks"?
>
> In this section I see sample command:
>
> # sysctl kern.geom.debugflags=17
>
> but I can't understand why this kernel tunable should be 17?
>
> If I will look through the /usr/src/sys/geom/geom_kern.c
>
> I will see this:
> "...
> TUNABLE_INT("kern.geom.debugflags", &g_debugflags);
> ..."
>
> and in /usr/src/sys/geom/geom_subr.c
>
> I will see this:
> "...
>       /* If foot-shooting is enabled, any open on rank#1 is OK */
>        if ((g_debugflags & 16) && pp->geom->rank == 1);
> ..."
>
> So I think that it should be 16 or I looked for it in inappropriate files.
>

17 additionally enables the first bit to trace G_T_TOPOLOGY events.
There is a full list in geom/geom_int.h:
/*
 * 1    G_T_TOPOLOGY
 * 2    G_T_BIO
 * 4    G_T_ACCESS
 * 8    (unused)
 * 16   Allow footshooting on rank#1 providers
 * 32   G_T_DETAILS
 */

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