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288fd4e56e
This patch extends the RAM session interface with the ability to allocate DMA buffers. The client specifies the type of RAM dataspace to allocate via the new 'cached' argument of the 'Ram_session::alloc()' function. By default, 'cached' is true, which correponds to the common case and the original behavior. When setting 'cached' to 'false', core takes the precautions needed to register the memory as uncached in the page table of each process that has the dataspace attached. Currently, the support for allocating DMA buffers is implemented for Fiasco.OC only. On x86 platforms, it is generally not needed. But on platforms with more relaxed cache coherence (such as ARM), user-level device drivers should always use uncacheable memory for DMA transactions.
109 lines
3.2 KiB
C++
109 lines
3.2 KiB
C++
/*
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* \brief Core-internal dataspace representation on Linux
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* \author Norman Feske
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* \date 2006-05-19
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*
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* On Linux userland, we do not deal with physical memory. Instead,
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* we create a file for each dataspace that is to be mmapped.
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* Therefore, the allocator is not really used for allocating
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* memory but only as a container for quota.
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*/
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/*
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* Copyright (C) 2006-2012 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _CORE__INCLUDE__LINUX__DATASPACE_COMPONENT_H_
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#define _CORE__INCLUDE__LINUX__DATASPACE_COMPONENT_H_
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#include <linux_dataspace/linux_dataspace.h>
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#include <util/string.h>
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#include <util/misc_math.h>
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#include <base/rpc_server.h>
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#include <base/printf.h>
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namespace Genode {
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/**
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* Deriving classes can own a dataspace to implement conditional behavior
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*/
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class Dataspace_owner { };
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class Dataspace_component : public Rpc_object<Linux_dataspace>
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{
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private:
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size_t _size; /* size of dataspace in bytes */
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addr_t _addr; /* meaningless on linux */
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Filename _fname; /* filename for mmap */
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bool _writable; /* false if read-only */
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/* Holds the dataspace owner if a distinction between owner and
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* others is necessary on the dataspace, otherwise it is 0 */
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Dataspace_owner * _owner;
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public:
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/**
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* Constructor
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*/
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Dataspace_component(size_t size, addr_t addr,
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bool /* write_combined */, bool writable,
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Dataspace_owner * owner)
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: _size(size), _addr(addr), _writable(writable),
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_owner(owner) { }
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/**
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* Default constructor returns invalid dataspace
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*/
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Dataspace_component() : _size(0), _addr(0), _writable(false),
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_owner(0) { }
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/**
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* This constructor is only provided for compatibility
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* reasons and should not be used.
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*/
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Dataspace_component(size_t size, addr_t core_local_addr,
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addr_t phys_addr, bool write_combined,
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bool writable, Dataspace_owner * _owner)
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: _size(size), _addr(phys_addr), _owner(_owner)
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{
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PWRN("Should only be used for IOMEM and not within Linux.");
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}
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/**
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* Define/request corresponding filename of dataspace
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*
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* To use dataspaces as shared memory objects on Linux, we have to
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* assign a file to each dataspace. This way, multiple Linux process
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* can mmap this file.
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*/
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void fname(const char *fname) { strncpy(_fname.buf, fname, sizeof(_fname.buf)); }
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/**
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* Check if dataspace is owned by a specified object
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*/
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bool owner(Dataspace_owner * const o) const { return _owner == o; }
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/*************************
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** Dataspace interface **
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*************************/
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size_t size() { return _size; }
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addr_t phys_addr() { return _addr; }
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bool writable() { return _writable; }
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/****************************************
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** Linux-specific dataspace interface **
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****************************************/
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Filename fname() { return _fname; }
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};
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}
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#endif /* _CORE__INCLUDE__LINUX__DATASPACE_COMPONENT_H_ */
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