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Quoting from Loongson2FUserGuide.pdf:
5.22.1 Hazards
The processor detects most of the pipeline hazards in hardware, including
CP0 hazards and load hazards. No NOP instructions are required to correct
instruction sequences.
Signed-off-by: Zhang Le <r0bertz@gentoo.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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The Alchemy manuals state:
"All pipeline hazards and dependencies are enforced by hardware interlocks
so that any sequence of instructions is guaranteed to execute correctly.
Therefore, it is not necessary to pad legacy MIPS hazards (such as
load delay slots and coprocessor accesses) with NOPs."
Run-tested on Au12x0, without any ill effects.
Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Current VR5500 processor support lacks of some functions which are
expected to be configured/synthesized on arch initialization.
Here're some VR5500A spec notes:
* All execution hazards are handled in hardware.
* Once VR5500A stops the operation of the pipeline by WAIT instruction,
it could return from the standby mode only when either a reset, NMI
request, or all enabled interrupts is/are detected. In other words,
if interrupts are disabled by Status.IE=0, it keeps in standby mode
even when interrupts are internally asserted.
Notes on WAIT: The operation of the processor is undefined if WAIT
insn is in the branch delay slot. The operation is also undefined
if WAIT insn is executed when Status.EXL and Status.ERL are set to 1.
* VR5500A core only implements the Load prefetch.
With these changes, it boots fine.
Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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For Cavium CPU, we treat the same as R10000, in that all hazards
are dealt with in hardware.
Signed-off-by: Tomaso Paoletti <tpaoletti@caviumnetworks.com>
Signed-off-by: Paul Gortmaker <Paul.Gortmaker@windriver.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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