The Freescale (was Motorola) M68K family of processors implements the full 68000 processor instruction set. The Freescale ColdFire family of processors is a modern derivative of the 68000 processor family. They are mainly targeted at embedded applications, and are all System-On-Chip (SOC) devices, as opposed to stand alone CPUs. They implement a subset of the original 68000 processor instruction set. If you anticipate running this kernel on a computer with a classic MC68xxx processor, select M68KCLASSIC. If you anticipate running this kernel on a computer with a ColdFire processor, select COLDFIRE.
The Freescale (was Motorola) 68000 CPU is the first generation of the well known M68K family of processors. The CPU core as well as being available as a stand alone CPU was also used in many System-On-Chip devices (eg 68328, 68302, etc). It does not contain a paging MMU.
The Freescale (was then Motorola) CPU32 is a CPU core that is based on the 68020 processor. For the most part it is used in System-On-Chip parts, and does not contain a paging MMU.
If you anticipate running this kernel on a computer with a MC68020 processor, say Y. Otherwise, say N. Note that the 68020 requires a 68851 MMU (Memory Management Unit) to run Linux/m68k, except on the Sun 3, which provides its own version.
If you anticipate running this kernel on a computer with a MC68030 processor, say Y. Otherwise, say N. Note that a MC68EC030 will not work, as it does not include an MMU (Memory Management Unit).
If you anticipate running this kernel on a computer with a MC68LC040 or MC68040 processor, say Y. Otherwise, say N. Note that an MC68EC040 will not work, as it does not include an MMU (Memory Management Unit).
If you anticipate running this kernel on a computer with a MC68060 processor, say Y. Otherwise, say N.
Motorola 68328 processor support.
Motorola 68EX328 processor support.
Motorola 68VZ328 processor support.
Select the type of ColdFire System-on-Chip (SoC) that you want to build for.
Motorola ColdFire 5206 processor support.
Motorola ColdFire 5206e processor support.
Freescale Coldfire 5207/5208 processor support.
Freescale Coldfire 5230/1/2/4/5 processor support
Motorola ColdFire 5249 processor support.
Freescale (Motorola) Coldfire 5251/5253 processor support.
Freescale (Motorola) ColdFire 5270/5271 processor support.
Motorola ColdFire 5272 processor support.
Freescale (Motorola) ColdFire 5274/5275 processor support.
Motorola ColdFire 5280/5282 processor support.
Motorola ColdFire 5307 processor support.
Freescale (Motorola) ColdFire 532x processor support.
Freescale ColdFire 537x processor support.
Motorola ColdFire 5407 processor support.
Freescale ColdFire 5470/5471/5472/5473/5474/5475 processor support.
Freescale ColdFire 5480/5481/5482/5483/5484/5485 processor support.
Freescale Coldfire 54410/54415/54416/54417/54418 processor support.
At some point in the future, this will cause floating-point math instructions to be emulated by the kernel on machines that lack a floating-point math coprocessor. Thrill-seekers and chronically sleep-deprived psychotic hacker types can say Y now, everyone else should probably wait a while.
The fpu uses normally a few bit more during calculations for correct rounding, the emulator can (often) do the same but this extra calculation can cost quite some time, so you can disable it here. The emulator will then "only" calculate with a 64 bit mantissa and round slightly incorrect, what is more than enough for normal usage.
This option prevents any floating-point instructions from being compiled into the kernel, thereby the kernel doesn't save any floating point context anymore during task switches, so this kernel will only be usable on machines without a floating-point math coprocessor. This makes the kernel a bit faster as no tests needs to be executed whether a floating-point instruction in the kernel should be executed or not.
This gives you access to some advanced options for the CPU. The defaults should be fine for most users, but these options may make it possible for you to improve performance somewhat if you know what you are doing. Note that the answer to this question won't directly affect the kernel: saying N will just cause the configurator to skip all the questions about these options. Most users should say N to this question.
This allows to use certain instructions that work with indivisible read-modify-write bus cycles. While this is faster than the workaround of disabling interrupts, it can conflict with DMA ( = direct memory access) on many Amiga systems, and it is also said to destabilize other machines. It is very likely that this will cause serious problems on any Amiga or Atari Medusa if set. The only configuration where it should work are 68030-based Ataris, where it apparently improves performance. But you've been warned! Unless you really know what you are doing, say N. Try Y only if you're quite adventurous.
Ignore all but the first contiguous chunk of physical memory for VM purposes. This will save a few bytes kernel size and may speed up some operations. When this option os set to N, you may want to lower "Maximum zone order" to save memory that could be wasted for unused memory map. Say N if not sure.
The kernel memory allocator divides physically contiguous memory blocks into "zones", where each zone is a power of two number of pages. This option selects the largest power of two that the kernel keeps in the memory allocator. If you need to allocate very large blocks of physically contiguous memory, then you may need to increase this value. For systems that have holes in their physical address space this value also defines the minimal size of the hole that allows freeing unused memory map. This config option is actually maximum order plus one. For example, a value of 11 means that the largest free memory block is 2^10 pages.
The 68060 generally uses copyback caching of recently accessed data. Copyback caching means that memory writes will be held in an on-chip cache and only written back to memory some time later. Saying Y here will force supervisor (kernel) accesses to use writethrough caching. Writethrough caching means that data is written to memory straight away, so that cache and memory data always agree. Writethrough caching is less efficient, but is needed for some drivers on 68060 based systems where the 68060 bus snooping signal is hardwired on. The 53c710 SCSI driver is known to suffer from this problem.
Define the CPU clock frequency in use. This is the core clock frequency, it may or may not be the same as the external clock crystal fitted to your board. Some processors have an internal PLL and can have their frequency programmed at run time, others use internal dividers. In general the kernel won't setup a PLL if it is fitted (there are some exceptions). This value will be specific to the exact CPU that you are using.
Build support for the older revision ColdFire 5307 silicon. Specifically this is the 1H55J mask revision.
Use all of the ColdFire CPU cache memory as an instruction cache.
Use all of the ColdFire CPU cache memory as a data cache.
Split the ColdFire CPU cache, and use half as an instruction cache and half as a data cache.
The ColdFire CPU cache is set into Write-through mode.
The ColdFire CPU cache is set into Copy-back mode.