Question on block driver operation buffer

[Daniel Castro]

Hello,

When an int 13 operation is handles (suppose read), you are supposed
to get sector X up until sector Y, where X is lba and count is Y. But
I wonder, the buffer is the size of the operation? or is it a
predefined size that never changes? I tend to incline for the later
one, but how can I determine the size?

Thanks,

Daniel