Update the physio man page to better reflect reality.

PR:		docs/30603
Reviewed by:	phk
MFC after:	3 days

1 files changed, 14 insertions, 37 deletions

diff --git a/share/man/man9/physio.9 b/share/man/man9/physio.9
index 9e9eeda..add4c64 100644
--- a/share/man/man9/physio.9
+++ b/share/man/man9/physio.9
@@ -54,16 +54,12 @@ The
 .Fn physio
 is a helper function typically called from character device read and write
 routines to start I/O on a user process buffer.
-It calls back on the
-provided
-.Fa strategy
-routine one or more times to complete the transfer described by
-.Fa uio .
-The maximum amount of data to transfer with each call to
-.Fa strategy
-is determined by the
-.Fa minphys
-routine.
+The maximum amount of data to transfer with each call 
+is determined by: 
+.Bd -literal 
+dev->si_iosize_max 
+.Ed
+.Pp
 Since
 .Fa uio
 normally describes user space addresses,
@@ -74,38 +70,11 @@ flag on the process.
 .Fn physio
 always awaits the completion of the entire requested transfer before
 returning, unless an error condition is detected earlier.
-In all cases,
-the buffer passed in
-.Fa bp
-is locked (marked as
-.Dq busy )
-for the duration of the entire transfer.
 .Pp
 A break-down of the arguments follows:
 .Bl -tag -width indent
-.It Fa strategy
-The device strategy routine to call for each chunk of data to initiate
-device I/O.
-.It Fa bp
-The buffer to use with the strategy routine.
-The buffer flags will have
-.Dv B_BUSY ,
-and
-.Dv B_PHYS
-set when passed to the strategy routine.
-If
-.Dv NULL ,
-a buffer is allocated from a system pool.
 .It Fa dev
 The device number identifying the device to interact with.
-.It Fa flags
-Direction of transfer; the only valid settings are
-.Dv B_READ
-or
-.Dv B_WRITE .
-.It Fa minphys
-A device specific routine called to determine the maximum transfer size
-that the device's strategy routine can handle.
 .It Fa uio
 The description of the entire transfer as requested by the user process.
 Currently, the results of passing a
@@ -139,3 +108,11 @@ condition.
 .Sh SEE ALSO
 .Xr read 2 ,
 .Xr write 2
+.Sh HISTORY
+The 
+.Xr physio 9 
+manual page is originally from NetBSD with minor changes for applicability 
+with FreeBSD.
+.Pp
+The physio(9) call has been completely re-written for providing higher
+I/O performance, and better paging performance.