badaddr(9r) [osf1 man page]

BADADDR(9r)															       BADADDR(9r)

NAME

       BADADDR - General: Probes the address during device autoconfiguration

SYNOPSIS

       int BADADDR(
	       caddr_t addr,
	       int length,
	       struct bus_ctlr_common *ptr );

ARGUMENTS

       Specifies  the  address of the device registers or memory.  Specifies the length (in bytes) of the data to be checked.  Valid values are 1,
       2, and 4 on 32-bit machines and 4 and 8 on 64-bit machines.  Specifies a pointer to a bus_ctlr_common structure. You cast this argument	as
       a pointer to either a bus or controller structure.

DESCRIPTION

       The  BADADDR  routine generates a call to a machine-dependent routine that does a read access check of the data at the supplied address and
       dismisses any machine check exception that may result from the attempted access. You call this routine to probe for memory or  I/O  devices
       at a specified address during device autoconfiguration.

NOTES

       You  can  use  BADADDR  in  device drivers that are statically configured into the kernel. However, you cannot use BADADDR if the driver is
       dynamically configured into the kernel.

       If you implement the driver to be both statically and dynamically configured, you can declare a variable and use it to control the call	to
       BADADDR.

       The following code fragment shows the use of such a variable used in the probe routine for the /dev/none driver:

       .  .  .

	    if (none_is_dynamic) {

	    /* Code to handle tasks associated with a dynamically *
	     * configured driver */

       .  .  .

	    }
	    else {

	   /* Code to handle tasks (including the call to BADADDR) *
	    * associated with a statically configured driver *
	    * including call to BADADDR 	   */
	   }

       .  .  .

       The  EISA  and  ISA buses do not generate a machine check when BADADDR performs a read access to a nonexistent location. These buses always
       return success when BADADDR performs a read access to their address space.

       For the PCI bus and the VMEbus, you must do the following before calling BADADDR: Call the iohandle_to_phys routine to convert the I/O han-
       dle to a valid system physical address Call the PHYS_TO_KSEG routine to convert the valid system physical address to a kernel-unmapped vir-
       tual address Call the BADADDR routine, passing this kernel-unmapped virtual address as the first argument

RETURN VALUES

       The BADADDR routine returns the value 0 (zero) if the data is accessible or a nonzero value if the data is not accessible.

																       BADADDR(9r)

Check Out this Related Man Page

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)

Linux and UNIX Man Pages

badaddr(9r) [osf1 man page]

Check Out this Related Man Page