KENG%NUSEEV.BITNET@cunyvm.cuny.edu (03/13/90)
Can anyone tell me more about allocation of buffer in system V. The AT&T device driver manual says that after obtaining a buffer using geteblk() I must fill in the b_flags & b_bcount fields. My questions are: Since the b_bcount field specify the amount of bytes to be transfered, can I specify any number of bytes as the situation arise or the buffer size is fixed by the system. (buf.h or anywhere else didn't mention the system buffer size). The AT&T device driver reference manual for system V says that some of the fields in the buf structure is not changable by the driver when the buffer is allocated by the kernel unless the buffer is allocated by the driver. I don't see the different between a buffer allocated by the kernel from one allocated by the driver since the call *geteblk() obtain buffer from the system free buffer list. The machine I am developing the device driver on is Motorola sysV/68. Many thanks in advance. keng@nuseev.bitnet