IOREMAP_NOCACHE(9) Public Functions Provided IOREMAP_NOCACHE(9)NAME
ioremap_nocache - map bus memory into CPU space
void __iomem * ioremap_nocache(resource_size_t offset, unsigned long size);
bus address of the memory
size of the resource to map
ioremap performs a platform specific sequence of operations to make bus memory CPU accessible via the readb/readw/readl/writeb/
writew/writel functions and the other mmio helpers. The returned address is not guaranteed to be usable directly as a virtual address.
If the area you are trying to map is a PCI BAR you should have a look at pci_iomap.
Matthew Wilcox <firstname.lastname@example.org>
Alan Cox <email@example.com>
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 IOREMAP_NOCACHE(9)
Check Out this Related Man Page
SF_BUF(9) BSD Kernel Developer's Manual SF_BUF(9)NAME
sf_buf -- manage temporary kernel address space mapping for memory pages
struct sf_buf *
sf_buf_alloc(struct vm_page *m, int flags);
sf_buf_free(struct sf_buf *sf);
sf_buf_kva(struct sf_buf *sf);
struct vm_page *
sf_buf_page(struct sf_buf *sf);
The sf_buf interface, historically the sendfile(2) buffer interface, allows kernel subsystems to manage temporary kernel address space map-
pings for physical memory pages. On systems with a direct memory map region (allowing all physical pages to be visible in the kernel address
space at all times), the struct sf_buf will point to an address in the direct map region; on systems without a direct memory map region, the
struct sf_buf will manage a temporary kernel address space mapping valid for the lifetime of the struct sf_buf.
Call sf_buf_alloc() to allocate a struct sf_buf for a physical memory page. sf_buf_alloc() is not responsible for arranging for the page to
be present in physical memory; the caller should already have arranged for the page to be wired, i.e., by calling vm_page_wire(9). Several
flags may be passed to sf_buf_alloc():
SFB_CATCH Cause sf_buf_alloc() to abort and return NULL if a signal is received waiting for a struct sf_buf to become available.
SFB_NOWAIT Cause sf_buf_alloc() to return NULL rather than sleeping if a struct sf_buf is not immediately available.
SFB_CPUPRIVATE Cause sf_buf_alloc() to only arrange that the temporary mapping be valid on the current CPU, avoiding unnecessary TLB shoot-
downs for mappings that will only be accessed on a single CPU at a time. The caller must ensure that accesses to the virtual
address occur only on the CPU from which sf_buf_alloc() was invoked, perhaps by using sched_pin().
Call sf_buf_kva() to return a kernel mapped address for the page.
Call sf_buf_page() to return a pointer to the page originally passed into sf_buf_alloc().
Call sf_buf_free() to release the struct sf_buf reference. The caller is responsible for releasing any wiring they have previously acquired
on the physical page; sf_buf_free() releases only the temporary kernel address space mapping, not the page itself.
Uses of this interface include managing mappings of borrowed pages from user memory, such as in zero-copy socket I/O, or pages of memory from
the buffer cache referenced by mbuf external storage for sendfile(2).
SEE ALSO sendfile(2), vm_page_wire(9)AUTHORS
The struct sf_buf API was designed and implemented by Alan L. Cox. This manual page was written by Robert N. M. Watson.
BSD January 28, 2007 BSD
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