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

[Fabiano Rosas]

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.

> If hmp_info_via is generic enough and not device-specific, it could be moved 
> out of mos6522.c to somewhere else.

Perhaps it would be easier to just have a stub for the 64 bits build? Do
HMP commands get in any way enabled/disabled depending on the emulated
hw that is available? It might be ok to have a hmp_info_via that is a
noop in 64bit.