Re: [PATCH 01/10] vl.c: Do not add isa-parallel if it's not present

[Fabiano Rosas]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> On 6/2/23 15:08, Fabiano Rosas wrote:
>> Currently the isa-parallel driver is always added by default
>> regardless of the presence of the actual code in the build, which can
>> lead to a crash:
>> 
>> qemu-system-i386: unknown type 'isa-parallel'
>> Aborted (core dumped)
>> 
>> Check for the presence of the QOM class and do not include
>> isa-parallel by default if it's not found.
>> 
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>>   softmmu/vl.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/softmmu/vl.c b/softmmu/vl.c
>> index 9177d95d4e..614e6cf66e 100644
>> --- a/softmmu/vl.c
>> +++ b/softmmu/vl.c
>> @@ -1269,7 +1269,8 @@ static void qemu_disable_default_devices(void)
>>       if (!has_defaults || machine_class->no_serial) {
>>           default_serial = 0;
>>       }
>> -    if (!has_defaults || machine_class->no_parallel) {
>> +    if (!has_defaults || machine_class->no_parallel ||
>> +        !object_class_by_name("isa-parallel")) {
>>           default_parallel = 0;
>>       }
>>       if (!has_defaults || machine_class->no_floppy) {
>
> How is isa-parallel different, why not the other defaults?

I doesn't need to be different, I did it like this because I expected to
solve the others in the same way. Peter also flagged the inconsistency,
I'll add a Kconfig dependence like the others.

As to why the other defaults don't have this issue:

serial - for x86, already selected by CONFIG_PC;
         not used on arm;
parallel - for x86, should be selected by CONFIG_PC, I'll fix that on v2;
           not used on arm;
monitor - built in with char.c;
floppy - built in with blockdev.c;
sdcard - built in with blockdev.c;

cdrom - uses mc->block_default_type, so the CONFIG corresponding to that
        device should be selected.
net - verification is only done later during machine init, so the
      machine will need to provide a fallback;
vga - uses mc->default_display, so the CONFIG corresponding to that device
      should be selected.

These last three are addressed in other patches in this series (VGA_PCI, 
VIRTIO_*).