Re: [PATCH 3/4] hw/arm: Move armv7m_nvic.c to hw/arm/ and always enable it for arm builds

[Thomas Huth]

On 24/09/2019 11.42, Peter Maydell wrote:
> On Tue, 24 Sep 2019 at 05:44, Thomas Huth <address@hidden> wrote:
>>
>> On 23/09/2019 20.50, Peter Maydell wrote:
>>> On Mon, 23 Sep 2019 at 19:36, Thomas Huth <address@hidden> wrote:
>>>> Just try to change "obj-$(CONFIG_ARM_V7M) += armv7m_nvic.o" into
>>>> "obj-y += armv7m_nvic.o" in hw/int/Makefile.objs, and you'll see it break:
>>>>
>>>>   CC      alpha-softmmu/hw/intc/armv7m_nvic.o
>>>> In file included from include/hw/intc/armv7m_nvic.h:13,
>>>>                  from hw/intc/armv7m_nvic.c:19:
>>>> target/arm/cpu.h:1416: error: "FPCR_DZE" redefined [-Werror]
>>>>  #define FPCR_DZE    (1 << 9)    /* Divide by Zero exception trap enable */
>>>
>>> Sure, so don't define CONFIG_ARM_V7M in a default-config for
>>> a non-Arm architecture. Then you get the behaviour you want:
>>> the file is compiled only for the arm targets.
>>
>> Sigh, the point of this series is that it should also possible to
>> compile *without* CONFIG_ARM_V7M in default-configs if you want (and
>> yes, there are people out there who want to be able to compile a
>> minimalistic QEMU). It's currently not possible to disable this switch.
>> But ok, if you're not really interested in providing a possibility to
>> make qemu-system-arm a little bit more flexible in this regard, never
>> mind, I'll look into other issues instead.
> 
> No, I'm happy that we should be able to compile without CONFIG_ARM_V7M
> selected. I'm just confused about why you think this requires that
> we move this file out of hw/intc.
> 
> Case 1: arm target, CONFIG_ARM_V7M=y (presumably in a Kconfig world
> this is set by default if the user doesn't flip that switch):
> obj-$(CONFIG_ARM_V7M) expands to obj-y, file compiled, OK
> Case 2: arm target, CONFIG_ARM_V7M=n set by user via Kconfig:
> obj-$(CONFIG_ARM_V7M) expands to obj-n, file not compiled, which is
> also what we want
The problem is this "case 2" - it does not work. For example, try to
delete everything from default-configs/aarch64-softmmu.mak (especially
the "include"), and just stick a "CONFIG_ARM_VIRT=y" in there.
Linking of qemu-system-aarch64 will fail with lots of "undefined
reference to `armv7m_nvic_set_pending'" etc. messages.

 Thomas