On (Tue) Apr 06 2010 [10:34:29], Paul Brook wrote: > > On (Mon) Apr 05 2010 [17:33:38], Paul Brook wrote: > > > > There might be cases where a few bytes would have been sent out to char > > > > devices and some not. Currently the return values from qemu_chr_write() > > > > to char devs are only -1, indicating an error, or the complete length > > > > of the string passed. > > > > > > > > Make 'len' a pointer instead, and indicate how much of the string was > > > > written. The return value will either be the same as 'len' or a > > > > negative number indicating an error condition. > > > > > > This seems wrong. We should not be getting recoverable errors. > > > > I was thinking of adding a bool to CharDriverState to indicate if EAGAIN > > should be reported to the writer. This can be conveyed at the time of > > doing qemu_chr_add_handlers(). > > > > It would certainly be beneficial for consumers of virtio-serial to be > > notified of -EAGAIN so that the guest can be throttled till the chardev > > catches up with the data being sent. > > EAGAIN should only ever occur if no bytes are written.
Right. That, or just return 0 and let the caller handle the situation? Amit