Dean Reece writes:
> On Jun 2, 2005, at 12:59, Andrew Gallatin wrote:
> > I'd like to use a symbol (m_get_packets) which I can find only in
> > com.apple.kpi.unsupported. However, the name makes me a little
> > nervous, and I was wondering what was meant by "unsupported"
> >
> > Granted the name sounds less than encouraging, but at least
> > com.apple.kpi.unsupported does not seem to bump its
> > OSBundleCompatibleVersion on each minor release. This makes me
> > think that its at least a little more stable the com.apple.kernel.
> >
> > What's the policy for changes to things in com.apple.kpi.unsupported?
>
> It roughly translates to "no lifeguard on duty". We don't make any
> promises about the release-to-release compatibility of anything in
> the "unsupported" kext. From a practical standpoint, we tend to
> leave things in there alone (I don't think it changed from 10.4.0 to
> 10.4.1). When we do make changes there, it will usually be to remove
> symbols.
>
> So:
> 1) Don't use anything in com.apple.kpi.unsupported.
> 2) If you do use it, don't expect it to work in the next release
> 3) If it does work in the next release, goto 2
;)
Thanks for making me look harder. I think I may be able to get away with using
mbuf_allocpacket().
I'm trying to convert my ethernet driver from allocating a big cluster
for every slot as its used on each interrupt to allocating a large
number of big clusters after some low-water mark is reached. It looks
like mbuf_allocpacket(how, num_wanted * mbuf_stat.bigmclbytes, ....)
should return a chain of num_wanted big clusters with M_PKTHDR set in
just the first one. In some sense, this is ideal because for every
cluster but the first in a received jumbo frame, I currently end up
having clear the M_PKTHDR flag. So this should save me about 3
function calls per 9000 byte packet (remove 2 calls to mbuf_flags,
remove 2 calls to mbuf_setflags, and add one call to mbuf_setflags).
Now if I could just do the same thing for plain mbufs, I'd be a really
happy camper.. In fact, it would be really nice if I could control
the actual allocation size, since I can see wanting to use 2KB
clusters if somebody reduces my MTU to 1500 bytes.
Drew
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