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On Fri, Mar 26, 2004 at 10:09:15AM -0800, Matt Thomas wrote:
>=20
> On Mar 26, 2004, at 9:15 AM, Jonathan Stone wrote:
> >You're absolutely right about the assumptions I made with IPLs. I'd
> >respond that IPLs shoulid be explicity ordered; and the (macppc)
> >become less shabby. Or we could fix kcont to not rely on that
> >assumption; I haven't thought hard about how to do that.
>=20
> While I can see your point, I'm not sure I agree.  IPLs can map
> to hardware IPLs (think vax) and placing a restriction on ordering
> is not correct.
>=20
> Note that on i386 that higher IPLs do not block lower IPLs.  In a
> sense, they are independent.  IPL_NET blocks network interrupt but
> BIO or TTY interrupts may proceed.
>=20
> You can't compare IPL levels in NetBSD.

=46rom what I understand, we may need to change that on NetBSD for SMP. As I
understand it, yamt@ pointed out (and Jason concured) we will need a
strict lock hierarchy to avoid deadlock. This requirement will probably=20
translate to needing a hierarchy of IPL locks and thus a hierarchy of=20
spl's.

Take care,

Bill

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