Re: [Qemu-devel] [PATCH v4 3/4] hw/arm: add sunxi machine type

[Andreas Färber]

Hi,

Am 26.11.2013 10:22, schrieb Peter Crosthwaite:
> On Tue, Nov 26, 2013 at 5:22 PM, liguang <address@hidden> wrote:
>> Signed-off-by: liguang <address@hidden>
>> ---
>>  hw/arm/Makefile.objs |    1 +
>>  hw/arm/sunxi-soc.c   |   98 
>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 99 insertions(+), 0 deletions(-)
>>  create mode 100644 hw/arm/sunxi-soc.c
>>
>> diff --git a/hw/arm/Makefile.objs b/hw/arm/Makefile.objs
>> index 3671b42..f9f3071 100644
>> --- a/hw/arm/Makefile.objs
>> +++ b/hw/arm/Makefile.objs
>> @@ -5,3 +5,4 @@ obj-y += tosa.o versatilepb.o vexpress.o xilinx_zynq.o z2.o
>>
>>  obj-y += armv7m.o exynos4210.o pxa2xx.o pxa2xx_gpio.o pxa2xx_pic.o
>>  obj-y += omap1.o omap2.o strongarm.o
>> +obj-y += sunxi-soc.o
>> diff --git a/hw/arm/sunxi-soc.c b/hw/arm/sunxi-soc.c
>> new file mode 100644
>> index 0000000..b45af6d
>> --- /dev/null
>> +++ b/hw/arm/sunxi-soc.c
>> @@ -0,0 +1,98 @@
>> +/*
>> + * Allwinner sunxi series SoC emulation
>> + *
>> + * Copyright (C) 2013 Li Guang
>> + * Written by Li Guang <address@hidden>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License as published by the
>> + * Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful, but 
>> WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
>> + * for more details.
>> + */
>> +
>> +#include "hw/sysbus.h"
>> +#include "hw/devices.h"
>> +#include "hw/boards.h"
>> +#include "hw/arm/arm.h"
>> +#include "hw/ptimer.h"
>> +#include "hw/char/serial.h"
>> +#include "hw/timer/sunxi-pit.h"
>> +#include "hw/intc/sunxi-pic.h"
>> +
>> +#include "sysemu/sysemu.h"
>> +#include "exec/address-spaces.h"
>> +
>> +
>> +#define SUNXI_PIC_REG_BASE 0x01c20400
>> +#define SUNXI_PIT_REG_BASE 0x01c20c00
>> +#define SUNXI_UART0_REG_BASE 0x01c28000
>> +
>> +static struct arm_boot_info sunxi_binfo = {
>> +    .loader_start = 0x40000000,
>> +    .board_id = 0x1008,
>> +};
>> +
>> +static void sunxi_init(QEMUMachineInitArgs *args)
> 
> I would check with Andreas/PMM on what the go is with SoCs regarding
> container devices and boards. My (vague) understanding is that SoCs
> should be container devices and boards instantiate those containers
> with off-chip connectivity. This seems flat to me, with everything on
> board level.

Yes, thanks, that matches what I was going to comment. But I think it's
even more complicated: To my understanding, "sunxi" is the name of a
community effort [1] to clean up and upstream the BSP kernels from
Allwinner, so it sounds as if this was an attempt to write an emulation
for that kernel family while naming everything "sunxi" when in fact the
SoCs are called Axx [2] (with A1x = sun4i, A2x = sun5i, A3x = sun6i but
no literal "sunxi" AFAIK) and boards include Cubieboard, Cubieboard2,
Cubieboard3/Cubietruck [3] and whatever tablets etc. are out there.
(CC'ing Bamvor)

That's a lesson we learned from the old "prep" machine: Please name
things after real hardware, only then can it later be verified whether
the modeling is actually correct or which changes need to be performed.

A practical aspect of modeling SoCs correctly is that they can more
easily be reused across boards or modules, and you don't need to mess
with machine-level cpu_model if you have a fixed SoC-CPU mapping.

You may want to consult the recent DIGIC or earlier Faraday series or my
Tegra2 repository for examples of how to implement this paradigm.
I believe the composition tree naming wrt "cortex" and the MPCore was
still open, hopefully PMM can comment on his current preferences.

And thanks for your efforts, from a distribution viewpoint I am looking
forward to testing our kernels and images with this.

Regards,
Andreas

[1] http://linux-sunxi.org/Main_Page
[2] http://www.allwinnertech.com/en/product/A-Serial.html
[3] http://cubieboard.org/

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