Re: [Qemu-devel] qemu-system-sh4 vs qemu-system-arm/i386 default behavior

[Tom Rini]

On Wed, Nov 30, 2016 at 10:12:09AM +0100, Thomas Huth wrote:
> On 30.11.2016 09:02, Aurelien Jarno wrote:
> > On 2016-11-30 08:33, Thomas Huth wrote:
> >> On 30.11.2016 02:01, Tom Rini wrote:
> >>> Hey all,
> >>>
> >>> I'm trying to make use of the r2d platform for U-Boot testing via QEMU.
> >>> After applying a series[1] I can use the kernel.org sh4 toolchain to get
> >>> a u-boot.bin that runs, mostly.  I say mostly as first of all I have to
> >>> pass "-monitor null -serial null -serial stdio -nographic" to
> >>> qemu-system-sh4 and in that order for me to get output from U-Boot on
> >>> the prompt.  On other platforms such as arm and vexpress or i386 and the
> >>> 'pc' machine I do not need to do this.  Does anyone have any idea why
> >>> this might be and where to start poking in the code to fix this?
> > 
> > The reason is that u-boot and the linux kernel do not have the same way
> > to number the serial port than the physical hardware. Therefore u-boot
> > and the Linux kernel use the second physical serial port .The question is
> > whether we should number our ports from the software (or part of the
> > sofrware) or hardware point of view.
> 
> OK, thanks for the explanation, that makes sense now. ... maybe we
> should put this information on a SH4 machine page under
> http://qemu-project.org/Documentation/Platforms so that users have a
> possibility to understand this serial port numbering?

I'm still a bit confused, sorry.  Digging around a bit I guess what is
happening is that serial_hds[0] is being used, but Linux and U-Boot
expect to use serial_hds[1] and that's what the above combination of
arguments is getting me?  How would I go about saying in a more simple
form perhaps, to use the second described port not the first described
port?  Thanks!

-- 
Tom

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