[U-Boot] [PATCH RFC] sandbox: Add 64-bit sandbox

[Mario Six]

Hi Simon,

On Fri, Dec 29, 2017 at 4:13 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Mario,
>
> On 20 December 2017 at 07:31, Mario Six <mario.six at gdsys.cc> wrote:
>> From: Mario Six <six at gdsys.cc>
>>
>> To debug device tree issues involving 32- and 64-bit platforms, it is useful to
>> have a generic 64-bit platform available.
>>
>> Add a version of the sandbox that uses 64-bit integers for its physical
>> addresses as well as a modified device tree.
>>
>> Signed-off-by: Mario Six <mario.six at gdsys.cc>
>>
>> ---
>>  arch/sandbox/Kconfig             |   6 +
>>  arch/sandbox/cpu/cpu.c           |   2 +-
>>  arch/sandbox/dts/Makefile        |   4 +
>>  arch/sandbox/dts/sandbox64.dts   | 317 +++++++++++++++++++++++++++++++++++++++
>>  arch/sandbox/include/asm/io.h    |   6 +
>>  arch/sandbox/include/asm/types.h |  14 +-
>>  cmd/demo.c                       |   6 +-
>>  configs/sandbox64_defconfig      | 200 ++++++++++++++++++++++++
>>  drivers/demo/demo-simple.c       |   2 +-
>>  9 files changed, 550 insertions(+), 7 deletions(-)
>>  create mode 100644 arch/sandbox/dts/sandbox64.dts
>>  create mode 100644 configs/sandbox64_defconfig
>
> Reviewed-by: Simon Glass <sjg at chromium.org>
>
> Can you please update the sandbox README?
>

Sure, I'll extend the README.

> Also, how does this play with CONFIG_SANDBOX_64BIT and CONFIG_PHYS_64BIT ?
>

Yeah, the names of the config options are all a bit confusing (hence why I
added the RFC to see if someone may have a better idea). Setting the
CONFIG_PHYS_64BIT is not strictly necessary for the 64-bit sandbox, but some
architectures use the option to decide whether they run on a 32- or 64-bit
system, so I thought it was consistent to also set it, just in case. The
CONFIG_SANDBOX_64BIT option causes a 64-bit sandbox *binary* to be built. This
binary still uses 32-bit-wide types in the device tree (phys_addr_t and
phys_size_t, mostly, so the width of the physical addresses are still 32-bit),
so that's not what we want in this case. I decided to override the type
definitions in arch/sandbox/include/asm/types.h based on CONFIG_SANDBOX64
directly, since I didn't want to introduce yet another option that has the
words sandbox and 64 in its name. But it's pretty confusing still, I admit.

Maybe we could rename CONFIG_SANDBOX_64BIT to CONFIG_HOST_64BIT, and use
CONFIG_PHYS_64BIT to control the width of the physical addresses in types.h
(which is what it is used for in arch/arm/include/asm/types.h now that I'm
taking a closer look); that would at least make the names congruent with their
actual semantics. We would then have the options CONFIG_HOST_64BIT,
CONFIG_PHYS_64BIT, and CONFIG_SANDBOX64 as the "board option".

Maybe that's a cleaner solution?

> Regards,
> Simon
>

Best regards,
Mario