Linux 4.2 Kernel Gets Port To New Processor Architecture

[phoronix]

Phoronix: Linux 4.2 Kernel Gets Port To New Processor Architecture

The latest pull request to be submitted for Linux 4.2 is providing a new processor architecture port...

http://www.phoronix.com/scan.php?page=news_item&px=Linux-4.2-Renesas-H8-300

[gens]

i thought linux cant run on 8bit processors by default

[macemoneta]

The H8/300 is a 32-bit CPU:

https://en.wikipedia.org/wiki/H8_Family

[sobkas]

The H8/300 is a 32-bit CPU:
https://en.wikipedia.org/wiki/H8_Family

"Subfamilies include the 8/16-bit H8/300 and H8/500, the 16/32-bit H8/300H and H8S and the 32-bit H8SX series"

After reading commits I think it adds support for H8/300H and H8S

+config CPU_H8300H
+ bool
+
+config CPU_H8S
+ bool
+
more:
+cflags-$(CONFIG_CPU_H8300H) := -mh
+aflags-$(CONFIG_CPU_H8300H) := -mh -Wa,--mach=h8300h
+ldflags-$(CONFIG_CPU_H8300H) := -mh8300helf_linux
+cflags-$(CONFIG_CPU_H8S) := -ms
+aflags-$(CONFIG_CPU_H8S) := -ms -Wa,--mach=h8300s
+ldflags-$(CONFIG_CPU_H8S) := -mh8300self_linux
+
+KBUILD_CFLAGS += $(cflags-y)
+KBUILD_CFLAGS += -mint32 -fno-builtin
+KBUILD_CFLAGS += -D__linux__
+KBUILD_CFLAGS += -DUTS_SYSNAME="uClinux"

So no 8-bit cpus

[uid313]

I wonder why Renesas have both SuperH and H8.
Why don't they just ditch one architecture?
Or ditch both architectures and adopt ARM or MIPS instead?

[blubbaer]

I wonder why Renesas have both SuperH and H8.
Why don't they just ditch one architecture?
Or ditch both architectures and adopt ARM or MIPS instead?

Both architectures are well-established. So they are probably used in many products with long life cycles. Also each architecture targets a different market segment.

Why do you think the 8051 is still used and produced? The market for 8bit and 16bit microcontroller is quite different then the one for 32bit microcontroller.

[mlau]

I wonder why Renesas have both SuperH and H8.
Why don't they just ditch one architecture?
Or ditch both architectures and adopt ARM or MIPS instead?

They did ditch SH in favor of ARM: They took their SoCs, ripped out the SH4a core and put an ARM core in its place, but left everything else untouched. It's now called R-mobile or R-car. A lot of patents concerning the SH core are about to expire, and Renesas has abandoned the architecture a few years ago.

Not all H8 can run Linux. It's basically a very beefed up Mikrocontroller, with quirky (japanese) function Blocks, but very nice to work with and very powerful. Iirc they're used as ACPI embedded controllers in a wide variety of Laptops, and were initially developed to control electric Motors.
To give you an idea what you can do with them: I developed a pacman game on a h8s/2377 using the onchip pwm/timer and DACs to drive a VGA monitor, to use as a demo at tradeshows.