1# SPDX-License-Identifier: GPL-2.0 2 3config SH_STANDARD_BIOS 4 bool "Use LinuxSH standard BIOS" 5 help 6 Say Y here if your target has the gdb-sh-stub 7 package from www.m17n.org (or any conforming standard LinuxSH BIOS) 8 in FLASH or EPROM. The kernel will use standard BIOS calls during 9 boot for various housekeeping tasks (including calls to read and 10 write characters to a system console, get a MAC address from an 11 on-board Ethernet interface, and shut down the hardware). Note this 12 does not work with machines with an existing operating system in 13 mask ROM and no flash (WindowsCE machines fall in this category). 14 If unsure, say N. 15 16config STACK_DEBUG 17 bool "Check for stack overflows" 18 depends on DEBUG_KERNEL && PRINTK 19 help 20 This option will cause messages to be printed if free stack space 21 drops below a certain limit. Saying Y here will add overhead to 22 every function call and will therefore incur a major 23 performance hit. Most users should say N. 24 25config EARLY_PRINTK 26 bool "Early printk" 27 depends on SH_STANDARD_BIOS 28 help 29 Say Y here to redirect kernel printk messages to the serial port 30 used by the SH-IPL bootloader, starting very early in the boot 31 process and ending when the kernel's serial console is initialised. 32 This option is only useful while porting the kernel to a new machine, 33 when the kernel may crash or hang before the serial console is 34 initialised. If unsure, say N. 35 36config 4KSTACKS 37 bool "Use 4Kb for kernel stacks instead of 8Kb" 38 depends on DEBUG_KERNEL && (MMU || BROKEN) && !PAGE_SIZE_64KB 39 help 40 If you say Y here the kernel will use a 4Kb stacksize for the 41 kernel stack attached to each process/thread. This facilitates 42 running more threads on a system and also reduces the pressure 43 on the VM subsystem for higher order allocations. This option 44 will also use IRQ stacks to compensate for the reduced stackspace. 45 46config IRQSTACKS 47 bool "Use separate kernel stacks when processing interrupts" 48 depends on DEBUG_KERNEL && BROKEN 49 help 50 If you say Y here the kernel will use separate kernel stacks 51 for handling hard and soft interrupts. This can help avoid 52 overflowing the process kernel stacks. 53 54config DUMP_CODE 55 bool "Show disassembly of nearby code in register dumps" 56 depends on DEBUG_KERNEL 57 default y if DEBUG_BUGVERBOSE 58 default n 59 help 60 This prints out a code trace of the instructions leading up to 61 the faulting instruction as a debugging aid. As this does grow 62 the kernel in size a bit, most users will want to say N here. 63 64 Those looking for more verbose debugging output should say Y. 65 66config DWARF_UNWINDER 67 bool "Enable the DWARF unwinder for stacktraces" 68 depends on DEBUG_KERNEL 69 select FRAME_POINTER 70 default n 71 help 72 Enabling this option will make stacktraces more accurate, at 73 the cost of an increase in overall kernel size. 74 75config SH_NO_BSS_INIT 76 bool "Avoid zeroing BSS (to speed-up startup on suitable platforms)" 77 depends on DEBUG_KERNEL 78 default n 79 help 80 If running in painfully slow environments, such as an RTL 81 simulation or from remote memory via SHdebug, where the memory 82 can already be guaranteed to ber zeroed on boot, say Y. 83 84 For all other cases, say N. If this option seems perplexing, or 85 you aren't sure, say N. 86 87config MCOUNT 88 def_bool y 89 depends on STACK_DEBUG || FUNCTION_TRACER 90