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 gernal the kernel won't setup a PLL
- if it is fitted (there are some expections). This value will be
+ 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.
config CLOCK_DIV
running more threads on a system and also reduces the pressure
on the VM subsystem for higher order allocations.
-choice
- prompt "RAM size"
- default AUTO
-
-config RAMAUTO
- bool "AUTO"
- ---help---
- Configure the RAM size on your platform. Many platforms can auto
- detect this, on those choose the AUTO option. Otherwise set the
- RAM size you intend using.
+comment "RAM configuration"
-config RAM4MB
- bool "4MiB"
+config RAMBASE
+ hex "Address of the base of RAM"
+ default "0"
help
- Set RAM size to be 4MiB.
+ Define the address that RAM starts at. On many platforms this is
+ 0, the base of the address space. And this is the default. Some
+ platforms choose to setup their RAM at other addresses within the
+ processor address space.
-config RAM8MB
- bool "8MiB"
+config RAMSIZE
+ hex "Size of RAM (in bytes)"
+ default "0x400000"
help
- Set RAM size to be 8MiB.
+ Define the size of the system RAM. If you select 0 then the
+ kernel will try to probe the RAM size at runtime. This is not
+ supported on all CPU types.
-config RAM16MB
- bool "16MiB"
+config VECTORBASE
+ hex "Address of the base of system vectors"
+ default "0"
help
- Set RAM size to be 16MiB.
+ Define the address of the system vectors. Commonly this is
+ put at the start of RAM, but it doesn't have to be. On ColdFire
+ platforms this address is programmed into the VBR register, thus
+ actually setting the address to use.
-config RAM32MB
- bool "32MiB"
+config KERNELBASE
+ hex "Address of the base of kernel code"
+ default "0x400"
help
- Set RAM size to be 32MiB.
-
-endchoice
+ Typically on m68k systems the kernel will not start at the base
+ of RAM, but usually some small offset from it. Define the start
+ address of the kernel here. The most common setup will have the
+ processor vectors at the base of RAM and then the start of the
+ kernel. On some platforms some RAM is reserved for boot loaders
+ and the kernel starts after that. The 0x400 default was based on
+ a system with the RAM based at address 0, and leaving enough room
+ for the theoretical maximum number of 256 vectors.
choice
prompt "RAM bus width"
config RAMAUTOBIT
bool "AUTO"
- ---help---
+ help
Select the physical RAM data bus size. Not needed on most platforms,
so you can generally choose AUTO.
endchoice
+comment "ROM configuration"
+
+config ROM
+ bool "Specify ROM linker regions"
+ default n
+ help
+ Define a ROM region for the linker script. This creates a kernel
+ that can be stored in flash, with possibly the text, and data
+ regions being copied out to RAM at startup.
+
+config ROMBASE
+ hex "Address of the base of ROM device"
+ default "0"
+ depends on ROM
+ help
+ Define the address that the ROM region starts at. Some platforms
+ use this to set their chip select region accordingly for the boot
+ device.
+
+config ROMVEC
+ hex "Address of the base of the ROM vectors"
+ default "0"
+ depends on ROM
+ help
+ This is almost always the same as the base of the ROM. Since on all
+ 68000 type varients the vectors are at the base of the boot device
+ on system startup.
+
+config ROMVECSIZE
+ hex "Size of ROM vector region (in bytes)"
+ default "0x400"
+ depends on ROM
+ help
+ Define the size of the vector region in ROM. For most 68000
+ varients this would be 0x400 bytes in size. Set to 0 if you do
+ not want a vector region at the start of the ROM.
+
+config ROMSTART
+ hex "Address of the base of system image in ROM"
+ default "0x400"
+ depends on ROM
+ help
+ Define the start address of the system image in ROM. Commonly this
+ is strait after the ROM vectors.
+
+config ROMSIZE
+ hex "Size of the ROM device"
+ default "0x100000"
+ depends on ROM
+ help
+ Size of the ROM device. On some platforms this is used to setup
+ the chip select that controls the boot ROM device.
+
choice
prompt "Kernel executes from"
---help---
config ROMKERNEL
bool "ROM"
help
- The kernel will be resident in FLASH/ROM when running.
+ The kernel will be resident in FLASH/ROM when running. This is
+ often referred to as Execute-in-Place (XIP), since the kernel
+ code executes from the position it is stored in the FLASH/ROM.
endchoice
projects / powerpc.git / blobdiff