From owner-freebsd-alpha  Tue Jul 18  0:12: 1 2000
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Subject: Re: fxp0 hangs on a PC164 using STABLE 
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> 
>    I wonder - does the Alpha CPU have support for locked read-modify-write
> type operations? I'm thinking that perhaps that might be a better way to
> fix the problem.

Funny you should say that (see below) I'm a little unsure whether they
guarantee interlocks against I/O devices. Basically it allows you to set a
flag on an address and then later do a conditional store. If the lock is gone,
that adress was modified, and the conditional fails- so you can cycle back and
try again- kinda cool.