bcopy(9f) [opensolaris man page]
bcopy(9F) Kernel Functions for Drivers bcopy(9F) NAME
bcopy - copy data between address locations in the kernel SYNOPSIS
#include <sys/types.h> #include <sys/sunddi.h> void bcopy(const void *from, void *to, size_t bcount); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
from Source address from which the copy is made. to Destination address to which copy is made. bcount The number of bytes moved. DESCRIPTION
The bcopy() function copies bcount bytes from one kernel address to another. If the input and output addresses overlap, the command exe- cutes, but the results may not be as expected. Note that bcopy() should never be used to move data in or out of a user buffer, because it has no provision for handling page faults. The user address space can be swapped out at any time, and bcopy() always assumes that there will be no paging faults. If bcopy() attempts to access the user buffer when it is swapped out, the system will panic. It is safe to use bcopy() to move data within kernel space, since kernel space is never swapped out. CONTEXT
The bcopy() function can be called from user, interrupt, or kernel context. EXAMPLES
Example 1 Copying data between address locations in the kernel: An I/O request is made for data stored in a RAM disk. If the I/O operation is a read request, the data is copied from the RAM disk to a buffer (line 8). If it is a write request, the data is copied from a buffer to the RAM disk (line 15). bcopy() is used since both the RAM disk and the buffer are part of the kernel address space. 1 #define RAMDNBLK 1000 /* blocks in the RAM disk */ 2 #define RAMDBSIZ 512 /* bytes per block */ 3 char ramdblks[RAMDNBLK][RAMDBSIZ]; /* blocks forming RAM /* disk ... 4 5 if (bp->b_flags & B_READ) /* if read request, copy data */ 6 /* from RAM disk data block */ 7 /* to system buffer */ 8 bcopy(&ramdblks[bp->b_blkno][0], bp->b_un.b_addr, 9 bp->b_bcount); 10 11 else /* else write request, */ 12 /* copy data from a */ 13 /* system buffer to RAM disk */ 14 /* data block */ 15 bcopy(bp->b_un.b_addr, &ramdblks[bp->b_blkno][0], 16 bp->b_bcount); SEE ALSO
copyin(9F), copyout(9F) Writing Device Drivers WARNINGS
The from and to addresses must be within the kernel space. No range checking is done. If an address outside of the kernel space is selected, the driver may corrupt the system in an unpredictable way. SunOS 5.11 16 Jan 2006 bcopy(9F)
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biodone(9F) Kernel Functions for Drivers biodone(9F) NAME
biodone - release buffer after buffer I/O transfer and notify blocked threads SYNOPSIS
#include <sys/types.h> #include <sys/buf.h> void biodone(struct buf *bp); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
bp Pointer to a buf(9S) structure. DESCRIPTION
biodone() notifies blocked processes waiting for the I/O to complete, sets the B_DONE flag in the b_flags field of the buf(9S) structure, and releases the buffer if the I/O is asynchronous. biodone() is called by either the driver interrupt or strategy(9E) routines when a buf- fer I/O request is complete. biodone() provides the capability to call a completion routine if bp describes a kernel buffer. The address of the routine is specified in the b_iodone field of the buf(9S) structure. If such a routine is specified, biodone() calls it and returns without performing any other actions. Otherwise, it performs the steps above. CONTEXT
biodone() can be called from user or interrupt context. EXAMPLES
Generally, the first validation test performed by any block device strategy(9E) routine is a check for an end-of-file (EOF) condition. The strategy(9E) routine is responsible for determining an EOF condition when the device is accessed directly. If a read(2) request is made for one block beyond the limits of the device (line 10), it will report an EOF condition. Otherwise, if the request is outside the limits of the device, the routine will report an error condition. In either case, report the I/O operation as complete (line 27). 1 #define RAMDNBLK 1000 /* Number of blocks in RAM disk */ 2 #define RAMDBSIZ 512 /* Number of bytes per block */ 3 char ramdblks[RAMDNBLK][RAMDBSIZ]; /* Array containing RAM disk */ 4 5 static int 6 ramdstrategy(struct buf *bp) 7 { 8 daddr_t blkno = bp->b_blkno; /* get block number */ 9 10 if ((blkno < 0) || (blkno >= RAMDNBLK)) { 11 /* 12 * If requested block is outside RAM disk 13 * limits, test for EOF which could result 14 * from a direct (physio) request. 15 */ 16 if ((blkno == RAMDNBLK) && (bp->b_flags & B_READ)) { 17 /* 18 * If read is for block beyond RAM disk 19 * limits, mark EOF condition. 20 */ 21 bp->b_resid = bp->b_bcount; /* compute return value */ 22 23 } else { /* I/O attempt is beyond */ 24 bp->b_error = ENXIO; /* limits of RAM disk */ 25 bp->b_flags |= B_ERROR; /* return error */ 26 } 27 biodone(bp); /* mark I/O complete (B_DONE) */ 28 /* 29 * Wake any processes awaiting this I/O 30 * or release buffer for asynchronous 31 * (B_ASYNC) request. 32 */ 33 return(0); 34 } ... SEE ALSO
read(2), strategy(9E), biowait(9F), ddi_add_intr(9F), delay(9F), timeout(9F), untimeout(9F), buf(9S) Writing Device Drivers WARNINGS
After calling biodone(), bp is no longer available to be referred to by the driver. If the driver makes any reference to bp after calling biodone(), a panic may result. NOTES
Drivers that use the b_iodone field of the buf(9S) structure to specify a substitute completion routine should save the value of b_iodone before changing it, and then restore the old value before calling biodone() to release the buffer. SunOS 5.10 23 Apr 1996 biodone(9F)