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Allow reset vector to be set dynamically

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A chip's power-up sequence, or awake-from-sleep sequence, may wish to
set the reset PC based upon dynamic properties, e.g., the settings of
external pins.  Support this by passing the reset vector to the Coreplex.
ExampleTop simply hard-wires the reset vector, as was the case before.

Additionally, allow MTVEC to *not* be reset.  In most cases, including
riscv-tests, pk, and bbl, overriding MTVEC is one of the first things
that the boot sequence does.  So the reset value is superfluous.
This commit is contained in:
Andrew Waterman
2016-09-19 16:45:57 -07:00
parent e6c1bcfedd
commit d0572d6aab
9 changed files with 27 additions and 17 deletions
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13
src/main/scala/rocketchip/Utils.scala
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@ -168,21 +168,14 @@ object GenerateConfigString {
}
object GenerateBootROM {
def apply(p: Parameters) = {
def apply(p: Parameters, address: BigInt) = {
val romdata = Files.readAllBytes(Paths.get(p(BootROMFile)))
val rom = ByteBuffer.wrap(romdata)
rom.order(ByteOrder.LITTLE_ENDIAN)
// for now, have the reset vector jump straight to memory
val memBase = (
if (p(GlobalAddrMap) contains "mem") p(GlobalAddrMap)("mem")
else p(GlobalAddrMap)("io:int:dmem0")
).start
val resetToMemDist = memBase - p(ResetVector)
require(resetToMemDist == (resetToMemDist.toInt >> 12 << 12))
val configStringAddr = p(ResetVector).toInt + rom.capacity
require(address == address.toInt)
val configStringAddr = address.toInt + rom.capacity
require(rom.getInt(12) == 0,
"Config string address position should not be occupied by code")
rom.putInt(12, configStringAddr)