Amit Shah <amit.shah@xxxxxxxxxx> wrote:
Hi
>> > > +static void virtio_console_set_port_active(uint32_t idx)
>> > > +{
>> > > + int i = 0;
>> > > +
>> > > + while (idx / 32) {
>> > > + i++;
>> > > + idx -= 32;
>> > > + }
>> >
>> > It is just me, or you are doing a division + modulus in a very strange way?
>> >
>> > i = idx / 32;
>> > idx = idx % 32;
>> >
>> > ???
>
> Er, sorry I left this out.
>
> That won't work for MAX_PORTS > 32.
Why not?
idx = 42
i = 42 / 32 = 1
new_idx = 42 % 32 = 10
virtcon_config.ports_map[i] & (1U<< new_idx)
it gives exactly the same same result than before.
What you are hardcoding is a "very" complex way of doing a division with
remainder, or have I lost something?
> But I guess I can just do
>
> i = idx / MAX_VIRTIO_CONSOLE_PORTS;
> idx = idx % MAX_VIRTIO_CONSOLE_PORTS;
>
>> > > static void virtio_console_save(QEMUFile *f, void *opaque)
>> > > {
>> > > VirtIOConsole *s = opaque;
>> > > + unsigned int i;
>> > >
>> > > + /* The virtio device */
>> > > virtio_save(&s->vdev, f);
>> > > + /* The PCI device */
>> > > + pci_device_save(s->dev, f);
>> >
>> > If you don't use pci here, virtio_save() should save your pci stuff
>> > here. See the ->load_config() stuff.
>> >
>> > Yeap, it can confuse anybody.
>>
>> Actually no. Since virtio rides on top of pci, I'd expect virtio_save to
>> save pci state too :-)
>>
>> I'll check this too.
>>
>> > For the new table based vmstate, fields need to live in an struct, in
>> > this case VirtIOConsole.
>> >
>> > Can you move virtcon_config and virtcon_ports to VirtIOConsole.
>>
>> In that case VirtIOConsole has to become a static (instead of being
>> allocated via the call to virtio_common_init. Doable.
>>
>> > > + /* The config space */
>> > > + qemu_put_be16s(f, &virtcon_config.cols);
>> > > + qemu_put_be16s(f, &virtcon_config.rows);
>> >
>> > > + qemu_put_be32s(f, &virtcon_config.max_nr_ports);
>> > > + qemu_put_be32s(f, &virtcon_config.nr_active_ports);
>> > > + for (i = 0; i < (le32_to_cpu(virtcon_config.max_nr_ports) + 31) / 32; i++) {
>> > > + qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > > + }
>> >
>> > Don't even try to save a couple of bytes, please.
>>
>> Sorry, don't understand this.
>>
>> >
>> > for (i = 0; i < (MAX_VIRTIO_CONSOLES + 31) / 32; i++) {
>> > qemu_put_be32s(f, &virtcon_config.ports_map[i]);
>> > }
>> >
>> > Same for load, please. Makes the translation to table based way easier.
>>
>> OK, maybe I now get it. You're asking me not to le32_to_cpu() here,
>> correct?
>>
>> I do it this way because we could be migrated from a host that supports
>> 64 max ports to a host that supports 128 max ports and then back to the
>> one that supports 64 max ports. :-)
>>
>> > > + /* Items in struct VirtIOConsole */
>> > > + qemu_put_be32s(f, &virtio_console->guest_features);
>> >
>> > here you mean s->guest_features, right?
>>
>> Right!
>>
>> > > + /* Items in struct VirtIOConsolePort */
>> > > + for (i = 0; i < le32_to_cpu(virtcon_config.max_nr_ports); i++) {
>> > > + qemu_put_byte(f, virtcon_ports[i].guest_connected);
>> > > + }
>> >
>> > If you want to optimize saving of this field, it is possible that it is
>> > a better idea to create another bitmap for it. What do you think?
>>
>> Yes, I wanted to do that as well. The same functions that compute the
>> modulo/division earlier can give us this thing as well. But it'll only
>> be used for loadvm/savevm. I expect the bool to continue to reside in
>> this struct for normal operation.
>>
>> > I can't see VMState adding support for bools any time soon, but arrays
>> > of bool is a possibility.
>>
>> Consider the RFE filed :-)
>>
>> > > @@ -128,19 +610,29 @@ VirtIODevice *virtio_console_init(DeviceState *dev)
>> > > VirtIOConsole *s;
>> > > s = (VirtIOConsole *)virtio_common_init("virtio-console",
>> > > VIRTIO_ID_CONSOLE,
>> > > - 0, sizeof(VirtIOConsole));
>> > > + sizeof(struct virtio_console_config),
>> > > + sizeof(VirtIOConsole));
>> >
>> > Here, you mean:
>> >
>> > VirtIODevice *d = virtio_common_init(....);
>> > VirtIOConsole *s = DO_UPCAST(VirtIOConsole, vdev, d);
>> >
>> > :)
>>
>> Again original code, not my contributions :-)
>>
>> > Creation of VirtIODevice *d is not necesary, I found it easier to
>> > understand but it is up to you.
>>
>> For virtio-serial, I statically allocated VirtIOSerial and had a vdev
>> pointer inside it which virtio_common_init gave me. I can do the same
>> here.
>>
>> > > if (s == NULL)
>> > > return NULL;
>> > >
>> >
>> > Once you are there, virtio_common_init() can't return NULL, fix it please.
>>
>> Original code. But I will take it.
>>
>> > > -#define MAX_VIRTIO_CONSOLES 1
>> > > +#define MAX_VIRTIO_CONSOLE_PORTS 64
>> >
>> > Require that this number is a multiple of 32, and you can simplify all
>> > the (foo + 31/32) staff.
>>
>> Sure, but it's better to be careful in a couple of places just because
>> we can be. Does (foo+31)/32 make it very difficult to read?
>>
>> Amit
>> --
>> http://log.amitshah.net/
>>
>>
>
> Amit
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