ReonV/bin/tkconfig/config.help

Name of configuration
CONFIG_CFG_NAME
  The VHDL name of the created configuration record. Must be a valid
  VHDL identifier.

Prompt for target technology
CONFIG_SYN_GENERIC
  Selects the target technology. The following are available:

  - Generic: Generic FPGA or ASIC targets if your synthesis tool
    is capable of infering RAMs and pads automatically.

  - ATC35: Atmel-Nantes 0.35 um rad-hard CMOS

  - ATC25: Atmel-Nantes 0.25 um rad-hard CMOS

  - ATC18: Atmel-Nantes 0.18 um rad-hard CMOS with Virage ram cells

  - FS90:  UMC with Faraday FS90 libraries

  - UMC-0.18 : UMC 0.18 um CMOS with Virtual Silicon libraries

  - TSMC-0.25: TSMC 0.25 um CMOS

  - Xilinx-Virtex: Xilinx Virtex libraries

  - Xilinx-Virtex2: Xilinx Virtex2 libraries

  - Actel ProAsic and Axellerator FPGAs

Infer ram
CONFIG_SYN_INFER_RAM
  Say Y here if you want the synthesis tool to infer your
  RAMs for cache memories and trace buffer. Say N to directly
  instantiate technology-specific RAM cells from the selected
  target technology package (tech_xxx.vhd).

Infer register file
CONFIG_SYN_INFER_REGF
  Say Y here if you want the synthesis tool to infer the RAMS in
  the register file. Say N to directly instantiate technology-
  specific RAM cells from the selected target technology package
  (tech_xxx.vhd).

Infer rom
CONFIG_SYN_INFER_ROM
  Say Y here if you want the synthesis tool to infer the 
  (optional) internal boot ROM. Say N to directly instantiate
  technology-specific ROM cells from the selected target
  technology package (tech_xxx.vhd). Most users should say Y
  here since only the Virtex package provides support for hard
  ROM cells, and then only through Coregen.

Infer pads
CONFIG_SYN_INFER_PADS
  Say Y here if you want the synthesis tool to infer pads.
  Say N to directly instantiate technology-specific pads from
  the selected target technology package (tech_xxx.vhd).

Infer multiplier
CONFIG_SYN_INFER_MULT
  Say Y here if you want the synthesis tool to infer a multiplier
  for the UMUL/SMUL instructions. Say N to use a structural 
  multiplier provided in multlib.vhd. FPGA targets should say Y
  here, ASIC targets should say N unless your synthesis tool can
  infer some really fast multiplier core.

Use dual-port RAMS for DSU trace buffer
CONFIG_SYN_TRACE_DPRAM
  Say Y here if you want to use dual-port RAMs instead of single-port
  RAMs for the DSU trace buffer. This will reduce the total number of
  RAM blocks. Note that the target tech package must have support for
  DPRAM's, which is currently only implemented for Virtex, ATC25, and
  TSMC025.

Improve register file write timing
CONFIG_SYN_RFTYPE
  If you say Y here, the register file write timing will be improved
  by clocking the write port on the rising edge, providing a whole
  cycle for write strobe generation. If you say N, both read and write
  ports will be clocked on the falling edge of the clock, simplifying
  timing analysis.

  This option is not implemented on all targets. Say Y when possible.

Use Virtex CLKDLL for clock synchronisation
CONFIG_CLK_VIRTEX
  Valid for all Spartan and Virtex targets. If enabled, the input
  clock will be re-synchronized using a Virtex CLKDLL macro. This
  will improve clock-to-output delays and allow scaling the clock
  with a factor 0.5, 1.0, or 2.0. This option also re-synchronizes
  the SDRAM clock, allowing the use of the SDRAM controller without
  the inverted-clock option. For this to work, connect SDCLK to PLLREF.

  WARNING: This option cannot be simulated unless you also compile
  the VHDL component libraries for the Virtex macro blocks (comes
  with the Xilinx ISE tool). Also, the input clock must be at
  least 24 MHz for the CKLDLL to work.

System clock multiplier
CONFIG_CLKDLL_1_2
  Scale the input clock with a factor of 0.5, 1.0, or 2.0. Useful
  when the target board has an oscillator with a too high (or low)
  frequency for your design. The divided clock will be used as the
  main clock for the whole processor (except PCI and ethernet clocks).

Use Virtex-II DCM for clock synchronisation
CONFIG_CLK_VIRTEX2
  Valid for Spartan2/Spartan3/Virtex2 targets. If enabled, the input
  clock will be re-synchronized using a Virtex DCM macro. This
  will improve clock-to-output delays and allow scaling the clock
  frequency. This option also re-synchronizes the SDRAM clock,
  allowing the use of the SDRAM controller without the inverted-clock
  option. For this to work, connect SDCLK to PLLREF.

  WARNING: This option cannot be simulated unless you also compile
  the VHDL component libraries for the Virtex macro blocks (comes
  with the Xilinx ISE tool).

System clock multiplier
CONFIG_DCM_2_3
  Scale the input clock with a factor of 2/3, 3/4, 1, 4/3, 3/2, 
  2, 3, and 4. Useful when the target board has an oscillator with a 
  too high (or low) frequency for your design. The divided clock will
  be used as the main clock for the whole processor (except PCI and 
  ethernet clocks). NOTE: the resulting frequency must be at least
  24 MHz or the DCM might not work (see Virtex-II datasheet).

Enable CLKDLL for PCI clock
CONFIG_PCI_DLL
  Say Y here to re-synchronize the PCI clock using a 
  Virtex BUFGDLL macro. Will improve PCI clock-to-output 
  delays on the expense of input-setup requirements.

Use PCI clock system clock
CONFIG_PCI_SYSCLK
  Say Y here to the PCI clock to generate the system clock.
  The PCI clock can be scaled using the DCM or CLKDLL to 
  generate a suitable processor clock.

Number of SPARC register windows
CONFIG_IU_NWINDOWS
  The SPARC architecture (and LEON) allows 2 - 32 register windows.
  However, any number except 8 will require that you modify and 
  recompile your run-time system or kernel. Unless you know what
  you are doing, use 8.

SPARC V8 multiply and divide instruction
CONFIG_IU_V8MULDIV
  If you say Y here, the SPARC V8 multiply and divide instructions
  will be implemented. The instructions are: UMUL, UMULCC, SMUL,
  SMULCC, UDIV, UDIVCC, SDIV, SDIVCC. In code containing frequent
  integer multiplications and divisions, significant performance
  increase can be achieved. Emulated floating-point operations will
  also benefit from this option.

  By default, the sparc-rtems-gcc compiler does not emit these
  instructions and your code must be compiled with -mv8 to see any
  performance increase. On the other hand, code compiled with -mv8
  will generate an illegal instruction trap when executed on processors
  with this option disabled.

  The divider consumes approximately 2 kgates, the size of the
  multiplier depends on the latency.

Multiplier latency
CONFIG_IU_MUL_LATENCY_1
  The multiplier used for UMUL/SMUL instructions can be implemented
  with 1, 2, 4, 5 or 35 cycles latency. Lower latency gives higher
  multiplication performance, but increases area and might reduce
  the maximum clock frequency. The best area/timing/performance
  compromise is usually 4 or 5. A latency of 5 cycles will use the
  same multiplier (16x16) as for 4 cycles, but with a pipeline register
  to improve timing.

Multiplier latency
CONFIG_IU_MUL_MAC
  If you say Y here, the SPARC V8e UMAC/SMAC (multiply-accumulate)
  instructions will be enabled. The instructions implement a
  single-cycle 16x16->32 bits multiply with a 40-bits accumulator.
  The details of these instructions can be found in the LEON manual,
  section 2.4. Note that the multiplier must be configured with 4
  cycles latency for this option to be enabled.

Load latency
CONFIG_IU_LDELAY
  Defines the pipeline load delay (= pipeline cycles before the data
  from a load instruction is available for the next instruction).
  One cycle gives best performance, but might create a critical path
  on targets with slow (data) cache memories. A 2-cycle delay can
  improve timing but will reduce performance with about 5 - 8%.
  All FPGA targets and most ASIC targets do fine with 1.

Icc interlock 
CONFIG_IU_ICCHOLD
  If you say Y here, a pipeline stall cycle will be introduced when
  an instruction that modifies the condition codes is directly followed
  by a branch instruction that uses these codes (BICC, TICC). The option
  reduces the performance with about 5% but significantly improves timing
  on FPGA targets. Recommendation: say Y on FPGA targets, N on ASIC targets.

Fast jump address generation
CONFIG_IU_FASTJUMP
  If you say Y here, jump address generation will accelerated by
  using a separate address adder. Will improve timing on most targets
  to the cost of approximately 300 gates. 

Fast instruction decoding
CONFIG_IU_FASTDECODE
  If you say Y here, instruction decode timing will be improved by adding
  some extra parallel logic. Useful when you have a critical path
  ending at the register file read address ports.

Register file power saving
CONFIG_IU_RFPOW
  If you say Y here, the read ports of the register file will be disabled
  when not used in an attempt to save power. Only implemented on TSMC-0.25,
  UMC-0.18 and UMC-FS90 targets. Might lead to a critical path to the
  register file read enable signal. If so, say N and the read ports will
  be permanently enabled. Also say N if saving a few gates feels better
  than saving a few milli-Watts.

Hardware watchpoints
CONFIG_IU_WATCHPOINTS
  The processor can have up to 4 hardware watchpoints, allowing to 
  create both data and instruction breakpoints at any memory location,
  also in PROM. Each watchpoint will use approximately 500 gates.
  Use 0 to disable the watchpoint function.

Processor implementation ID
CONFIG_IU_IMPL
  Each SPARC processor has a 4-bit implementation ID hardcoded in the
  processor status register (%psr). You should not use numbers 0 - 9
  which are used by existing implementations. The value 10 will be
  assigned to Gaisler Research use this value unless you have a
  compelling reason not to. In any case, do NOT use 1 since this
  number is used by ERC32 and will cause applications compiled with
  LECCS to fail.

Processor version ID
CONFIG_IU_VER
  Each SPARC processor has a 4-bit version ID hardcoded in the
  processor status register (%psr). Use 2 for LEON2.

Floating-point enable
CONFIG_FPU_ENABLE
  Say Y here to enable the floating-point unit. Note that only the
  (incomplete) LTH FPU is provided with the LEON VHDL model. The
  Gaisler GRFPU and the Meiko FPU are commercial cores and must be
  obtained separately. 

FPU selection
CONFIG_FPU_GRFPU
  Select between Gaisler Research's GRFPU, the Sun Meiko FPU core or 
  the open-source LTH core from Lund's University. The Meiko and GRFPU 
  are fully IEEE-754 compatible and supports all SPARC FPU instructions.
  The LTH FPU also supports IEEE-754, but does not implement the FMUL, 
  FDIV and FSQRT instructions and cannot (yet) be used for general 
  floating-point code.

FPU version ID
CONFIG_FPU_VER
  Each SPARC FPU has a 3-bit version ID hardcoded in the FPU status
  register (%fsr). Has no impact on operation or any (known) software.
  Use as you like, staying with 0 is safe.

Co-processor enable
CONFIG_CP_ENABLE
  Say Y here to enable the interface to a (custom) co-processor unit.
  Unless you actually want to add your own co-processor, say N.

Co-processor configuration
CONFIG_CP_CFG
  The VHDL name of the co-processor configuration to be used. Should
  exist in target.vhd.

Instruction cache associativity
CONFIG_ICACHE_ASSO1
  The instruction cache can be implemented as a multi-set cache with
  1 - 4 sets. Higher associativity usually increases the cache hit
  rate and thereby the performance. The downside is higher power
  consumption and increased gate-count for tag comparators.

  Note that a 1-set cache is effectively a direct-mapped cache.

Instruction cache set size
CONFIG_ICACHE_SZ1
  The size of each set in the instuction cache (kbytes). Valid values
  are 1 - 64 in binary steps. Note that the full range is only supported
  by the generic and virtex2 targets. Most target packages are limited
  to 2 - 16 kbyte. Large set size gives higher performance but might
  affect the maximum frequency (on ASIC targets). The total instruction
  cache size is the number of set multiplied with the set size.

Instruction cache line size
CONFIG_ICACHE_LZ16
  The instruction cache line size. Can be set to either 16 or 32
  bytes per line. Instruction caches typically benefit from larger
  line sizes, but on small caches, it migh be better with 16 bytes/line
  to limit eviction miss rate.

Instruction cache replacement algorithm
CONFIG_ICACHE_ALGORND
  Cache replacement algorithm for caches with 2 - 4 sets. The 'random'
  algorithm selects the set to evict randomly. The least-recently-used
  (LRR) algorithm evicts the set least recently replaced. The least-
  recently-used (LRU) algorithm evicts the set least recently accessed.
  The random algorithm uses a simple 1- or 2-bit counter to select
  the eviction set and has low area overhead. The LRR scheme uses one
  extra bit in the tag ram and has therefore also low area overhead.
  However, the LRR scheme can only be used with 2-set caches. The LRU
  scheme has typically the best performance but also highest area overhead.
  A 2-set LRU uses 1 flip-flop per line, a 3-set LRU uses 3 flip-flops
  per line, and a 4-set LRU uses 5 flip-flops per line to store the access
  history.

Instruction cache locking
CONFIG_ICACHE_LOCK
  Say Y here to enable cache locking in the instruction cache.
  Locking can be done on cache-line level, but will increase the
  width of the tag ram with one bit. If you don't know what
  locking is good for, it is safe to say N.

Data cache associativity
CONFIG_DCACHE_ASSO1
  The data cache can be implemented as a multi-set cache with
  1 - 4 sets. Higher associativity usually increases the cache hit
  rate and thereby the performance. The downside is higher power
  consumption and increased gate-count for tag comparators.

  Note that a 1-set cache is effectively a direct-mapped cache.

Data cache set size
CONFIG_DCACHE_SZ1
  The size of each set in the data cache (kbytes). Valid values are
  1 - 64 in binary steps. Note that the full range is only supported
  by the generic and virtex2 targets. Most target packages are limited
  to 2 - 16 kbyte. A large cache gives higher performance but the
  data cache is timing critical an a too large setting might affect
  the maximum frequency (on ASIC targets). The total data cache size
  is the number of set multiplied with the set size.

Data cache line size
CONFIG_DCACHE_LZ16
  The data cache line size. Can be set to either 16 or 32 bytes per
  line. A smaller line size gives better associativity and higher
  cache hit rate, but requires a larger tag memory.

Data cache replacement algorithm
CONFIG_DCACHE_ALGORND
  See the explanation for instruction cache replacement algorithm.

Data cache locking
CONFIG_DCACHE_LOCK
  Say Y here to enable cache locking in the data cache.
  Locking can be done on cache-line level, but will increase the
  width of the tag ram with one bit. If you don't know what
  locking is good for, it is safe to say N.

Data cache snooping
CONFIG_DCACHE_SNOOP
  Say Y here to enable data cache snooping on the AHB bus. Is only
  useful if you have additional AHB masters such as the DSU or a
  target PCI interface. Note that the target technology must support
  dual-port RAMs for this option to be enabled. Dual-port RAMS are
  currently supported on Virtex/2, ATC25, ATC18 and TSMC025 targets.

Data cache snooping implementation
CONFIG_DCACHE_SNOOP_SLOW
  Selects the snooping implementation. Use 'slow' if you don't have
  AHB slaves in cacheable areas which are capable of supporting
  zero-waitstates non-sequential write accesses. Otherwise use 'fast'
  and suffer a few kgates extra area.

Fast read-data generation
CONFIG_DCACHE_RFAST
  Say Y here to improve the data read timing in multi-set caches.
  FPGA implementations usually do fine with N, while ASIC
  implementations tuned for maximum frequency should say Y. Increases
  the area with about 200 gates per set.

Fast write-data generation
CONFIG_DCACHE_WFAST
  Say Y here to improve the timing of the data inputs to the data
  cache data memory in multi-set caches. FPGA implementations
  usually do fine with N, while ASIC implementations tuned for
  maximum frequency should say Y. Increases the area with about
  200 gates per set.

Local data ram
CONFIG_DCACHE_LRAM
  Say Y here to add a local ram to the data cache controller.
  Accesses to the ram (load/store) will be performed at 0 waitstates
  and store data will never be written back to the AHB bus.

Size of local data ram
CONFIG_DCACHE_LRAM_SZ1
  Defines the size of the local data ram in Kbytes. Note that most
  technology libraries do not support larger rams than 16 Kbyte.

Start address of local data ram
CONFIG_DCACHE_LRSTART
  Defines the 8 MSB bits of start address of the local data ram.
  By default set to 8f (start address = 0x8f000000), but any value
  (except 0) is possible. Note that the local data ram 'shadows'
  a 16 Mbyte block of the address space.

MMU enable
CONFIG_MMU_ENABLE
  Say Y here to enable the Memory Management Unit.

MMU split icache/dcache table lookaside buffer
CONFIG_MMU_COMBINED
  Select "combined" for a combined icache/dcache table lookaside buffer,
  "split" for a split icache/dcache table lookaside buffer

MMU tlb replacement scheme
CONFIG_MMU_REPARRAY
  Select "LRU" to use the "least recently used" algorithm for TLB
  replacement, or "Increment" for a simple incremental replacement
  scheme.

Combined i/dcache tlb
CONFIG_MMU_I2
  Select the number of entries for the instruction TLB, or the
  combined icache/dcache TLB if such is used.

Split tlb, dcache
CONFIG_MMU_D2
  Select the number of entries for the dcache TLB.

8-bit memory support
CONFIG_MCTRL_8BIT
  If you say Y here, the PROM/SRAM memory controller will support
  8-bit mode, i.e. operate from 8-bit devices as if they were 32-bit.
  Say N to save a few hundred gates.

16-bit memory support
CONFIG_MCTRL_16BIT
  If you say Y here, the PROM/SRAM memory controller will support
  16-bit mode, i.e. operate from 16-bit devices as if they were 32-bit.
  Say N to save a few hundred gates.

Write strobe feedback
CONFIG_MCTRL_WFB
  If you say Y here, the PROM/SRAM write strobes (WRITEN, WEN) will
  be used to enable the data bus drivers during write cycles. This
  will guarantee that the data is still valid on the rising edge of
  the write strobe. If you say N, the write strobes and the data bus
  drivers will be clocked on the rising edge, potentially creating
  a hold time problem in external memory or I/O. However, in all
  practical cases, there is enough capacitance in the data bus lines
  to keep the value stable for a few (many?) nano-seconds after the
  buffers have been disabled, making it safe to say N and remove a 
  combinational path in the netlist that might be difficult to 
  analyze.

Write strobe feedback
CONFIG_MCTRL_5CS
  If you say Y here, the 5th (RAMSN[4]) SRAM chip select signal will
  be enabled. If you don't intend to use it, say N and save some gates.

SDRAM controller enable
CONFIG_MCTRL_SDRAM
  Say Y here to enabled the PC100/PC133 SDRAM controller. If you don't
  intend to use SDRAM, say N and save about 1 kgates.

SDRAM controller inverted clock
CONFIG_MCTRL_SDRAM_INVCLK
  If you say Y here, the SDRAM clock will be inverted in respect to the
  system clock and the SDRAM signals. This will limit the SDRAM frequency
  to 50/66 MHz, but has the benefit that you will not need a PLL to
  generate the SDRAM clock. On FPGA targets, say Y. On ASIC targets,
  say N and tell your foundry to balance the SDRAM clock output.

SDRAM separate address buses
CONFIG_MCTRL_SDRAM_SEPBUS
  Say Y here if your SDRAM is connected through separate address
  and data buses (SA & SD). This is the case on the GR-CPCI-XC2V6000
  board, but not on the GR-PCI-XC2V3000 or Avnet XCV1500E boards.

Default AHB master
CONFIG_AHB_DEFMST
  Sets the default AHB master (see AMBA 2.0 specification for definition).
  Should not be set to a value larger than the number of AHB masters - 1.
  For highest processor performance, leave it at 0.

Support AHB split-transactions
CONFIG_AHB_SPLIT
  Say Y here to enable AHB split-transaction support in the AHB arbiter.
  Unless you actually have an AHB slave that can generate AHB split
  responses, say N and save some gates. None of the AHB slaves provided
  with LEON generates split, so N is a safe choice.

AHB status register enable
CONFIG_PERI_AHBSTAT
  If you want the AHB status register functionality say Y here.
  The register will catch the address and parameters of AHB transfers
  that are terminated with an error response. Saying N will save
  about 500 gates.

RAM write-protectionenable
CONFIG_PERI_WPROT
  If you want to enable RAM write protection (LEON manual 7.13) say Y here.
  Otherwise say N and save 1 kgates.

LEON configuration register
CONFIG_PERI_LCONF
  Enables the LEON configuration register that shows how the model was
  configured. The register is necessary for the test benches to run, and
  also needed by applications compiled with LECCS. Always say Y.

Secondary interrupt controller enable
CONFIG_PERI_IRQ2
  Say Y here to enable the secondary interrupt controller (LEON 
  manual 6.3). Routing of the interrupt sources is done in mcore.vhd.
  It is safe to say N.

Secondary interrupt controller configuration
CONFIG_PERI_IRQ2_CFG
  The VHDL name of the secondary interrupt controller configuration
  to be used. Should exist in target.vhd.

Watchdog enable
CONFIG_PERI_WDOG
  Say Y here to enable the watchdog functionallity in the timer module.
  Unless you need a watchdog, say N and save 200 gates.

On-chip ram
CONFIG_AHBRAM_ENABLE
  Say Y here to add a block on on-chip ram to the AHB bus. The ram
  will be attached at address 0x60000000.

On-chip ram size
CONFIG_AHBRAM_SZ1
  Set the size of the on-chip AHB ram. The ram is infered/instantiated
  as four byte-wide ram slices to allow byte and half-word write
  accesses. It is therefore essential that the target package can
  infer byte-wide rams. This is currently supported on the generic,
  virtex, virtex2, proasic and axellerator targets.

DSU enable
CONFIG_DSU_ENABLE
  The debug support unit (DSU) allows non-intrusive debugging and tracing
  of both executed instructions and AHB transfers. If you want to enable
  the DSU, say Y here and select the configuration below.

Trace buffer enable
CONFIG_DSU_TRACEBUF
  Say Y to enable the trace buffer. The buffer is not necessary for
  debugging, only for tracing instructions and data transfers.

Enable mixed tracing
CONFIG_DSU_MIXED_TRACE
  If you say Y here, simultaneous instruction and AHB tracing will be
  possible. A N will still allow tracing of both, but not simultaneously.

Size of trace buffer
CONFIG_DSU_TRACESZ64
  Select the number of entries on the trace buffer. For each entry, 
  16 bytes (128 bits) will be needed. A 128-entry buffer will need
  2 kbyte.

PCI interface enable
CONFIG_PCI_ENABLE
  To enable a PCI interface, say Y here.

PCI interface type
CONFIG_PCI_TARGET
  Three PCI cores are provided with this version of Leon: a simple
  target-only interface without fifos, a fast target interface with
  configurable fifos, and a full master-target core with fifos.
  The simple target-only interface is small and robust, and is suitable
  to be used for DSU communications via PCI. The other two cores core
  are suitable when high transfer rates or a master interface are needed.

PCI trace buffer
CONFIG_PCI_TRACE
  The PCI trace buffer implements a simple on-chip logic analyzer
  to trace the PCI signals. The PCI AD bus and most control signals
  are stored in a circular buffer, and can be read out by the DSU
  or any other AHB master. See the manual for detailed operation.
  Only available for target technologies with dual-port rams.

PCI trace buffer depth
CONFIG_PCI_TRACE256
  Select the number of entries in the PCI trace buffer. Each entry
  will use 6 bytes of on-chip (block) ram.

PCI FIFO depth
CONFIG_PCI_FIFO8
  The number words in the PCI FIFO buffers in the master-target 
  core. The master interface uses four 33-bit wide FIFOs, while the
  target interface uses two. 

Ethernet MAC enable
CONFIG_ETH_ENABLE
  Say Y here to enable a Ethernet MAC from OpenCores. The control
  registers of the MAC will be mapped to 0xb0000000.

Ethernet MAC transmitt FIFO depth
CONFIG_ETH_TXFIFO
  The number of 32-bit words in the transmitt FIFO. 8 words is a 
  good compromise.

Ethernet MAC receive FIFO depth
CONFIG_ETH_RXFIFO
  The number of 32-bit words in the receiver FIFO. 8 words is a 
  good compromise.

Ethernet MAC burts length
CONFIG_ETH_BURST
  The length of the burst on the AHB when moving data to and from
  the FIFOs. A good compromise is half of the FIFO depth.
  
Fault-tolerance enable
CONFIG_FT_ENABLE
  Say Y here to enable the fault-tolerance features in LEON-FT. If you
  only have access to the the public LGPL model, say N or the model
  will not compile. If you do have the LEON-FT model, say Y here
  even if you say N to all other options.

Boot selection
CONFIG_BOOT_EXTPROM
  The processor can be configured to boot from external memory, internal
  ROM, or both. The internal ROM contains by default the PMON monitor
  (LEON manual 11.8). If the 'both' option is selected, boot source will
  be controlled through PIO[4].

Default RAM read waitstates
CONFIG_BOOT_RWS
  If booting from internal ROM is selected, the memory controller will
  automatically initialise the SRAM read waitstates setting with this
  value (valid range is 0 - 3).

Default RAM write waitstates
CONFIG_BOOT_WWS
  If booting from internal ROM is selected, the memory controller will
  automatically initialise the SRAM write waitstates setting with this
  value (valid range is 0 - 3).

System clock
CONFIG_BOOT_SYSCLK
  If booting from internal ROM is selected, this value should reflect
  the system clock frequency. This will allow proper default
  initialisation of the timer unit and UART baud-rate generation.

UART baud rate
CONFIG_BOOT_BAUDRATE
  If booting from internal ROM is selected, use this value to 
  automatically set the UART baud-rate.

Select external baud-rate
CONFIG_BOOT_EXTBAUD
  If you say Y here and booting from internal ROM is selected, the UART
  baud-rate scaler register will be initialised from PIO[7:0].

Internal ROM addres bits
CONFIG_BOOT_PROMABITS
  Defines the with of the internal ROM address bus. 11 bits is enough
  for 2 kbytes.

UART debugging
CONFIG_DEBUG_UART
  During simulation, the output from the UARTs is printed on the
  simulator console. Since the ratio between the system clock and
  UART baud-rate is quite high, simulating UART output will be very
  slow. If you say Y here, the UARTs will print a character as soon
  as it is stored in the transmitter data register. The transmitter
  ready flag will be permanently set, speeding up simulation. However,
  the output on the UART tx line will be garbled.  Has not impact on
  synthesis, but will cause the LEON test bench to fail.

IU register tracing
CONFIG_DEBUG_IURF
  If you say Y here, all writes to the integer unit register file will be
  printed on the simulator console.

FPU register tracing
CONFIG_DEBUG_FPURF
  If you say Y here, all writes to the floating-point unit register file
  will be printed on the simulator console.

Continue on reset trap
CONFIG_DEBUG_NOHALT
  The SPARC standard mandates that when error mode is entered,
  the processor should be halted. If you say Y here, a reset trap
  (tt = 0x0) will be take on error mode and the processor will
  not be halted. Use only for testing, since it will not be
  possible to stop the processor with this option enabled!

32-bit program counters
CONFIG_DEBUG_PC32
  Since the LSB 2 bits of the program counters always are zero, they are
  normally not implemented. If you say Y here, the program counters will
  be implemented with full 32 bits, making debugging of the VHDL model
  much easier. Turn of this option for synthesis or you will be wasting
  area.