B_BUSY Indicates the buffer is in use. The driver must not change this flag
unless it allocated the buffer with getrbuf(9F) and no I/O
operation is in progress.
B_DONE Indicates the data transfer has completed. This flag is read-only.
B_ERROR Indicates an I/O transfer error. It is set in conjunction with the
b_error field. bioerror(9F) should be used in preference to
setting the B_ERROR bit.
B_PAGEIO Indicates the buffer is being used in a paged I/O request. See the
description of the b_un.b_addr field for more information. This
flag is read-only.
B_PHYS indicates the buffer header is being used for physical (direct) I/O
to a user data area. See the description of the b_un.b_addr field
for more information. This flag is read-only.
B_READ Indicates that data is to be read from the peripheral device into
main memory.
B_WRITE Indicates that the data is to be transferred from main memory to
the peripheral device. B_WRITE is a pseudo flag and cannot be
directly tested; it is only detected as the NOT form of B_READ.
av_forw and av_back can be used by the driver to link the buffer into driver work
lists.
b_bcount specifies the number of bytes to be transferred in both a paged and a
non-paged I/O request.
b_un.b_addr is the virtual address of the I/O request, unless B_PAGEIO is set. The
address is a kernel virtual address, unless B_PHYS is set, in which case it is a user
virtual address. If B_PAGEIO is set, b_un.b_addr contains kernel private data. Note
that either one of B_PHYS and B_PAGEIO, or neither, can be set, but not both.
b_blkno identifies which logical block on the device (the device is defined by the
device number) is to be accessed. The driver might have to convert this logical block
number to a physical location such as a cylinder, track, and sector of a disk. This is a
32-bit value. The driver should use b_blkno or b_lblkno, but not both.
b_lblkno identifies which logical block on the device (the device is defined by the
device number) is to be accessed. The driver might have to convert this logical block
number to a physical location such as a cylinder, track, and sector of a disk. This is a
64-bit value. The driver should use b_lblkno or b_blkno, but not both.
b_resid should be set to the number of bytes not transferred because of an error.
b_bufsize contains the size of the allocated buffer.
b_iodone identifies a specific biodone routine to be called by the driver when the
I/O is complete.
buf(9S)
20 man pages section 9: DDI and DKI Properties and Data Structures • Last Revised 19 Sep 2002
