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Re: Some basic queries
>2. PCI-X says that Retry should be avoided, because it is not guaranteed
>that the cycle will come again, but this constraint is not in Conventional
I believe this has been done to avoid
"retry thrashing" (a particular transaction
clogging all the bandwidth while other
requests are pending) that has been a problem
in PCI. Most PCI system have some upper count
of retry attempts to avoid this. In PCIX,
since retry is not guaranteed, master has
a choice of starting this transaction
later as a new transaction if other
transactions are pending.
>3. Some of the terminations in PCI such as disconnect without data,
>disconnect with data after n data phases have been altogether removed from
The new set of PCIX target initiated
terminations have effectively removed the
scopes of these terminations. In PCIX now
we have "Disconnect at Next ADB" which
means that only the terminations at
cacheline boundaries are permitted. This
has been done so that data transmission takes
place in chunks and a good throughput is
IMHO, this has largely simplified the
internal address calculations in a design.
"Principles of Verilog PLI" by Swapnajit Mittra.
Kluwer Academic Publishers. ISBN: 0-7923-8477-6
Available in all online bookstores.
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