Re: [Qemu-devel] qemu-system-sh4 -M r2d serial is broken.

[Rob Landley]

On 05/18/2017 06:01 PM, Aurelien Jarno wrote:
> On 2017-05-18 17:37, Rob Landley wrote:
>> On 05/18/2017 02:00 PM, Aurelien Jarno wrote:
>>> On 2017-05-18 11:08, Rob Landley wrote:
>>>> Serial input hangs after the first character in the 4.11 kernel:
>>>>
>>>>   http://www.spinics.net/lists/linux-sh/msg51183.html
>>>>
>>>> Because they enabled support for a buffer size thing QEMU doesn't
>>>> emulate right:
>>>>
>>>>   http://www.spinics.net/lists/linux-sh/msg51189.html
>>>
>>> Indeed the SCIF emulation in QEMU is quite limited. The problem is that
>>> it exposes many internal states to the software (and that's the same for
>>> the SH4 CPU in general), and that's not really compatible with quick
>>> emulation. In that case the timer should depend on the baud rate which
>>> we don't really emulate.
>>>
>>> I'll try to have a look, that said my test environment is stuck with
>>> kernel 4.8 due to the broken futex support on UP in kernel 4.9 (and
>>> that's not QEMU specific). I'll try to build a more recent kernel with
>>> additional patches.
>>
>> I thought Rich fixed that. Rich?
> 
> I have sent a patch already, but TTBOMK it hasn't been applied yet.
> 
> Aurelien

I poked Rich about the futex patch again today, he's been buried up to
his neck in work but has to flush his bugfix queue before -rc5 so that
should get sorted this week.

Also, how do I tell the kernel to read the persistent clock on r2d? Both
CONFIG_RTC_DRV_R9701 (from r2d defconfig) and CONFIG_RTC_DRV_SH give
error messages and fail to read anything at boot time.

If you need a new test environment (simple one that doesn't use futexes
that I'm aware of) https://github.com/landley/mkroot is nearing its
first release. You'll need to follow the README instructions to build
musl-cross-make toolchains and set up the mcm symlink, but then:

  ./cross.sh sh4 ./mkroot.sh kernel
  cd output/sh4
  ./qemu-sh4.sh

Should boot you to a shell prompt. And given that the root filesystem
builder (mkroot.sh) is ~300 lines of bash and module/kernel is another
300 lines (mostly a big target-specific if/else staircase), it shouldn't
be too hard to pull apart. :)

Right now sh4 is the only target in the release list that hasn't got the
full "boots to a shell prompt and exits when you type exit, clock is set
to correct time, block device works, network card works" functionality
list. (That's all working on arm64 armv5l armv7l i486 i686 mips mipsel
powerpc s390x x86-64.)

Rob