original_kernel/arch/tile/gxio/Kconfig

# Support direct access to TILE-Gx hardware from user space, via the
# gxio library, or from kernel space, via kernel IORPC support.
config TILE_GXIO
	bool
	depends on TILEGX
arch/tile: introduce GXIO IORPC framework for tilegx The GXIO I/O RPC subsystem handles exporting I/O hardware resources to Linux and to applications running under Linux. For instance, memory which is made available for I/O DMA must be mapped by an I/O TLB; that means that such memory must be locked down by Linux, so that it is not swapped or otherwise reused, as long as those I/O TLB entries are active. Similarly, configuring direct hardware access introduces new validation requirements. If a user application registers memory, Linux must ensure that the supplied virtual addresses are valid, and turn them into client physical addresses. Similarly, when Linux then supplies those client physical addresses to the Tilera hypervisor, it must in turn validate those before turning them into the real physical addresses which are required by the hardware. To the extent that these sorts of activities were required on previous TILE architecture processors, they were implemented in a device-specific fashion. This meant that every I/O device had its own Tilera hypervisor driver, its own Linux driver, and in some cases its own user-level library support. There was a large amount of more-or-less functionally identical code in different places, particularly in the different Linux drivers. For TILE-Gx, this support has been generalized into a common framework, known as the I/O RPC framework or just IORPC. The two "gxio" directories (one for headers, one for sources) start with just a few files in each with this infrastructure commit, but after adding support for the on-board I/O shims for networking, PCI, USB, crypto, compression, I2CS, etc., there end up being about 20 files in each directory. More information on the IORPC framework is in the <hv/iorpc.h> header, included in this commit. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> 2012-04-05 04:39:58 +08:00			`# Support direct access to TILE-Gx hardware from user space, via the`
			`# gxio library, or from kernel space, via kernel IORPC support.`
			`config TILE_GXIO`
			`bool`
			`depends on TILEGX`