Re: [PATCH] mos6522: fix linking error when CONFIG_MOS6522 is not set

[Fabiano Rosas]

Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> writes:

> On 03/05/2022 15:06, Fabiano Rosas wrote:
>
>> Murilo Opsfelder Araújo <muriloo@linux.ibm.com> writes:
>> 
>>> $ cat > configs/devices/rh-virtio.mak <<"EOF"
>>> CONFIG_VIRTIO=y
>>> CONFIG_VIRTIO_BALLOON=y
>>> CONFIG_VIRTIO_BLK=y
>>> CONFIG_VIRTIO_GPU=y
>>> CONFIG_VIRTIO_INPUT=y
>>> CONFIG_VIRTIO_INPUT_HOST=y
>>> CONFIG_VIRTIO_NET=y
>>> CONFIG_VIRTIO_RNG=y
>>> CONFIG_VIRTIO_SCSI=y
>>> CONFIG_VIRTIO_SERIAL=y
>>> EOF
>>>
>>> $ cat > configs/devices/ppc64-softmmu/ppc64-rh-devices.mak <<"EOF"
>>> include ../rh-virtio.mak
>>> CONFIG_DIMM=y
>>> CONFIG_MEM_DEVICE=y
>>> CONFIG_NVDIMM=y
>>> CONFIG_PCI=y
>>> CONFIG_PCI_DEVICES=y
>>> CONFIG_PCI_TESTDEV=y
>>> CONFIG_PCI_EXPRESS=y
>>> CONFIG_PSERIES=y
>>> CONFIG_SCSI=y
>>> CONFIG_SPAPR_VSCSI=y
>>> CONFIG_TEST_DEVICES=y
>>> CONFIG_USB=y
>>> CONFIG_USB_OHCI=y
>>> CONFIG_USB_OHCI_PCI=y
>>> CONFIG_USB_SMARTCARD=y
>>> CONFIG_USB_STORAGE_CORE=y
>>> CONFIG_USB_STORAGE_CLASSIC=y
>>> CONFIG_USB_XHCI=y
>>> CONFIG_USB_XHCI_NEC=y
>>> CONFIG_USB_XHCI_PCI=y
>>> CONFIG_VFIO=y
>>> CONFIG_VFIO_PCI=y
>>> CONFIG_VGA=y
>>> CONFIG_VGA_PCI=y
>>> CONFIG_VHOST_USER=y
>>> CONFIG_VIRTIO_PCI=y
>>> CONFIG_VIRTIO_VGA=y
>>> CONFIG_WDT_IB6300ESB=y
>>> CONFIG_XICS=y
>>> CONFIG_XIVE=y
>>> CONFIG_TPM=y
>>> CONFIG_TPM_SPAPR=y
>>> CONFIG_TPM_EMULATOR=y
>>> EOF
>>>
>>> $ mkdir build
>>> $ cd build
>>>
>> 
>> <snip>
>> 
>>> $ ../configure --without-default-devices 
>>> --with-devices-ppc64=ppc64-rh-devices --target-list=ppc64-softmmu
>>> $ make -j
>>> ...
>>> /usr/bin/ld: 
>>> libqemu-ppc64-softmmu.fa.p/monitor_misc.c.o:(.data.rel+0x3228): undefined 
>>> reference to `hmp_info_via'
>>> collect2: error: ld returned 1 exit status
>>>
>>> Since TARGET_PPC is defined when building target ppc64-softmmu, the 
>>> hmp_info_via will be referenced when processing the hmp-commands-info.hx.
>>> However, hmp_info_via implementation resides on hw/misc/mos6522.c, which is 
>>> built only if CONFIG_MOS6522 is defined, as per hw/misc/meson.build.
>> 
>> I think this particular problem you hit is due to the 64 bit devices
>> file including 32 bit as well:
>> 
>> $ cat configs/devices/ppc64-softmmu/default.mak
>> # Default configuration for ppc64-softmmu
>> 
>> # Include all 32-bit boards
>> include ../ppc-softmmu/default.mak <----- here
>> 
>> # For PowerNV
>> CONFIG_POWERNV=y
>> 
>> # For pSeries
>> CONFIG_PSERIES=y
>> ---
>> 
>> So ppc64-softmmu doesn't quite do what it says on the tin. I think in
>> the long run we need to revisit the conversation about whether to keep
>> the 32 & 64 bit builds separate. It is misleading that you're explicitly
>> excluding ppc-softmmu from the `--target-list`, but a some 32 bit stuff
>> still comes along implicitly.
>
> Unfortunately for historical reasons it isn't quite that simple: the mac99 
> machine in 
> hw/ppc/mac_newworld.c is both a 32-bit and a 64-bit machine, but with a 
> different PCI 
> host bridge and a 970 CPU if run from qemu-system-ppc64. Unfortunately it 
> pre-dates 
> my time working on QEMU's PPC Mac machines but I believe it was (is?) capable 
> of 
> booting Linux, even though I doubt it accurately represents a real machine.

Well, what you describe is fine in my view, the 64-bit machine uses
qemu-system-ppc64. If there is shared code with 32-bit, that is ok.

What I would like to understand is what is the community's direction
with this, do we want:

1) the 64-bit build to include all of the code and have it run all
   machines, or;

2) the 64-bit build to run only 64-bit machines and the 32-bit build to
   run only 32-bit machines.

There are things such as 'target_ulong' that go against #1, and this
thread shows that we're not doing #2 as well.

I know there have been discussions about this in the past but I couldn't
find them in the archives.