phys_to_kseg(9r) [osf1 man page]

PHYS_TO_KSEG(9r)														  PHYS_TO_KSEG(9r)

NAME

       PHYS_TO_KSEG - General: Converts a physical address to a kernel-unmapped virtual address

SYNOPSIS

       vm_offset_t PHYS_TO_KSEG(
	       vm_offset_t addr );

ARGUMENTS

       Specifies the physical address to convert to a kernel-unmapped virtual address.

DESCRIPTION

       The PHYS_TO_KSEG routine converts a kernel physical address to a kernel-unmapped virtual address.

EXAMPLE

       The following code fragment shows a call to PHYS_TO_KSEG:

       .  .  .

       caddr_t virt_addr;  [1] unsigned phys_addr; [2]

       .  .  .

	       virt_addr = PHYS_TO_KSEG(phys_addr); [3]

       .  .  .

       Declares a variable to store the virtual address returned by PHYS_TO_KSEG.  Declares a variable to store the physical address. This address
       might have been obtained from a call to KSEG_TO_PHYS.  Calls PHYS_TO_KSEG to convert  the  physical  address  to  a  corresponding  virtual
       address.

RETURN VALUES

       Upon successful completion, PHYS_TO_KSEG returns the virtual address associated with the specified physical address.

SEE ALSO

       Routines: IS_KSEG_VA(9r), KSEG_TO_PHYS(9r)

																  PHYS_TO_KSEG(9r)

svatophys(9r)															     svatophys(9r)

NAME

       svatophys - General: Converts a system virtual address to a physical address

SYNOPSIS

       kern_return_t svatophys(
	       vm_offset_t kern_addr,
	       vm_offset_t *phys_addr );

ARGUMENTS

       Specifies the kernel virtual address.  Specifies a pointer to the physical address to be filled in.

DESCRIPTION

       The  svatophys routine converts a system virtual address to the corresponding physical address. All address and data structure manipulation
       done within the kernel is performed using system virtual addresses.  Typically, system virtual addresses are a means  of  mapping  physical
       memory  and  I/O  space,  which often consists of device registers and DMA buffers. In contrast to this, devices are usually unaware of any
       virtual addressing and for this reason use physical addresses. You use the svatophys routine to perform this address translation.

       As an example of where you can use this address translation, a disk device driver can use DMA buffers to transfer blocks  of  data  to  the
       disk  (for  the case of a write operation). The data to be written to disk is present in system memory at a system virtual address known to
       the driver. To initiate the DMA operation, the disk driver can set up a command packet to specify a write operation to the underlying  disk
       controller  hardware.  This write command packet contains (among other things) the location of the DMA buffer as a physical address and the
       length of the buffer. Here, the driver calls the svatophys routine to translate the system virtual address of the DMA buffer to a  physical
       address in the command packet issued to the disk driver.

RETURN VALUES

       The  svatophys  routine returns the following: The address translation has been completed successfully.	Unable to perform address transla-
       tion. This value indicates that the address specified by the kern_addr argument is not a valid kernel or system virtual address.

																     svatophys(9r)