[J-core] working on SH-2 emulator.

[D. Jeff Dionne]

The driver does exist...  here is a print of my boot just a few min ago:

Open vmlinux OK
Use bootloader's DTB
RUN program
Linux version 4.6.0-00044-g127f81a-dirty (jeff at VirtualSuSE) (gcc version 5.3.0 (GCC) ) #2 SMP Sun Sep 4 07:28:34 EDT 2016
Boot params:
... MOUNT_ROOT_RDONLY - 00000001
... RAMDISK_FLAGS     - 00000000
... ORIG_ROOT_DEV     - 00000200
... LOADER_TYPE       - 00000001
... INITRD_START      - 00000000
... INITRD_SIZE       - 00000000
earlycon: uartlite_a0 at MMIO 0xabcd0100 (options '')
bootconsole [uartlite_a0] enabled
Booting machvec: devicetree

The relevant lines in .config are:

#
# Serial drivers
#
CONFIG_SERIAL_EARLYCON=y
# CONFIG_SERIAL_8250 is not set

#
# Non-8250 serial port support
#
# CONFIG_SERIAL_MAX3100 is not set
# CONFIG_SERIAL_MAX310X is not set
CONFIG_SERIAL_UARTLITE=y
CONFIG_SERIAL_UARTLITE_CONSOLE=y
# CONFIG_SERIAL_SH_SCI is not set
CONFIG_SERIAL_CORE=y
CONFIG_SERIAL_CORE_CONSOLE=y


> On Sep 6, 2016, at 4:04 PM, Rob Landley <rob at landley.net> wrote:
> 
> On 09/06/2016 12:53 AM, D. Jeff Dionne wrote:
>> On Sep 6, 2016, at 2:46 PM, BGB <cr88192 at gmail.com> wrote:
>> 
>> Oh, excellent.  This means you have passed all the CPU tests, and dropped into
>> a GDB stub.  Did you implement and test the J2 CAS instruction, or
> patch it out?
> 
> CAS an the two bit-shifts from sh3. (All mentioned on http://j-core.org
> but I really should have better docs.)
> 
> Alas, our arch/sh/configs/j2_defconfig does not appear to have
> EARLY_PRINTK set, most likely because we haven't got an early printk
> driver for our serial device. So you've got to get pretty far along in
> the kernel boot before it dumps the printk buffer out to the serial device.
> 
> (I remember Rich poking at that area before, but I don't remember how it
> turned out. Possibly it's just not enabled in the config?)
> 
> Rob