.\" .\" Copyright (c) 2004 Joseph Koshy .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' .\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED .\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE .\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .\" $FreeBSD: src/share/man/man9/contigmalloc.9,v 1.5 2005/01/21 08:36:40 ru Exp $ .\" $DragonFly: src/share/man/man9/contigmalloc.9,v 1.1 2008/01/19 08:23:17 swildner Exp $ .\" .Dd January 19, 2008 .Dt CONTIGMALLOC 9 .Os .Sh NAME .Nm contigmalloc , .Nm contigfree .Nd manage contiguous kernel physical memory .Sh SYNOPSIS .In sys/types.h .In sys/malloc.h .Ft "void *" .Fo contigmalloc .Fa "unsigned long size" .Fa "struct malloc_type *type" .Fa "int flags" .Fa "vm_paddr_t low" .Fa "vm_paddr_t high" .Fa "unsigned long alignment" .Fa "unsigned long boundary" .Fc .Ft void .Fo contigfree .Fa "void *addr" .Fa "unsigned long size" .Fa "struct malloc_type *type" .Fc .Sh DESCRIPTION The .Fn contigmalloc function allocates .Fa size bytes of contiguous physical memory that is aligned to .Fa alignment bytes, and which does not cross a boundary of .Fa boundary bytes. If successful, the allocation will reside between physical addresses .Fa low and .Fa high . The returned pointer points to a wired kernel virtual address range of .Fa size bytes allocated from the kernel virtual address (KVA) map. The .Fa type argument is ignored. .Pp The .Fa flags parameter modifies .Fn contigmalloc Ns Ap s behavior as follows: .Bl -tag -width ".Dv M_WAITOK" -offset indent .It Dv M_WAITOK Causes .Fn contigmalloc to try flushing the active page queue in its second pass. Note that (unlike .Fn kmalloc M_WAITOK ) .Fn contigmalloc M_WAITOK can still return NULL. .It Dv M_ZERO Causes the allocated physical memory to be zero filled. .El .Pp Other flags (if present) are ignored. .Pp The .Fn contigfree function deallocates memory allocated by a previous call to .Fn contigmalloc . .Sh IMPLEMENTATION NOTES The .Fn contigmalloc function does not sleep waiting for memory resources to be freed up, but instead scans available physical memory a small number of times for a suitably sized free address range before giving up. Memory allocation is done on a first-fit basis, starting from the top of the provided address range. .Sh RETURN VALUES The .Fn contigmalloc function returns a kernel virtual address if allocation succeeds, or .Dv NULL otherwise. .Sh EXAMPLES .Bd -literal void *p; p = contigmalloc(8192, M_DEVBUF, M_ZERO, 0, (1L << 22), 32 * 1024, 1024 * 1024); .Ed .Pp Ask for 8192 bytes of zero-filled memory residing between physical address 0 and 4194303 inclusive, aligned to a 32K boundary and not crossing a 1M address boundary. .Sh DIAGNOSTICS The .Fn contigmalloc function will panic if .Fa size is zero, or if .Fa alignment or .Fa boundary is not a power of two. .Sh SEE ALSO .Xr kmalloc 9