Snoop Under Boff# During A Cache Line-Fill Cycle - Intel Quark SoC X1000 Core Developer's Manual

Figure 117. Snoop under BOFF# during a Cache Line-Fill Cycle
CLK
BOFF#
EADS#
INV
HITM#
A31–A4
A3–A2
ADS#
BLAST#
CACHE#
RDY#
BRDY#
W/R#
An ADS# is always issued when a cycle resumes after being fractured by BOFF#. The
address of the fractured data transfer is reissued under this ADS#, and CACHE# is not
issued unless the fractured operation resumes from the first transfer (e.g., first
doubleword). If the system asserts BOFF# and RDY# simultaneously, as shown in clock
four on Figure
Back Enhanced Intel
and the line fill resumes with the x0h doubleword. ADS# initiates the resumption of the
line-fill operation in clock period 15. HITM# is de-asserted in the clock period following
the clock period in which the last RDY# or BRDY# of the write-back cycle is asserted.
Hence, HITM# is guaranteed to be de-asserted before the ADS# of the next cycle.
Figure 117
Burst cache line-fill cycles behave similarly to non-burst cache line-fill cycles when
snooping using BOFF#. If the system snoop hits the same line as the line being filled
(burst or non-burst), the Write-Back Enhanced Intel
assert HITM# and does not issue a snoop write-back cycle, because the line was not
modified, and the line fill resumes upon the de-assertion of BOFF#. However, the line
fill is cached only if INV is driven low during the snoop cycle.
®
Intel Quark SoC X1000 Core
Developer's Manual
236
1 2 3 4 5 6 7
Linefill †
4 0
†
To Processor
117, BOFF# dominates and RDY# is ignored. Consequently, the Write-
®
Quark SoC X1000 Core accepts only up to the x4h doubleword,
also shows the system asserting RDY# to indicate a non-burst line-fill cycle.
Intel
8 9 10 11 12 13 14 15
Write Back Cycle
0 4 C 8
®
Quark SoC X1000 Core does not
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Quark Core—Bus Operation
16 17 18 19 20 21 22 23
Line Fill Cycle Cont.
0 C 8
242202-154
October 2013
Order Number: 329679-001US