The modular lx_kit seperates the required back end functionality of the Linux emulation environment from the front end. Thereby each driver can reuse specific parts or supply more suitable implementations by itself. It is used to reduce the amount of redundant code in each driver. The lx_kit is split into several layers whose structure is as follows: The first layer in _repos/dde_linux/src/include/lx_emul_ contains those header files that provide the structural definitions and function declarations of the Linux API, e.g. _errno.h_ provides all error code values. The second layer in _repos/dde_linux/src/include/lx_emul/impl_ contains the implementation of selected functions, e.g. _slab.h_ provides the implementation of 'kmalloc()'. The lx_kit back end API is the third layer and provides the _Lx::Malloc_ interface (_repos/dde_linux/src/include/lx_kit/malloc.h_) which is used to implement 'kmalloc()'. There are several generic implementations of the lx_kit interfaces that can be used by a driver. A driver typically includes a 'lx_emul/impl/xyz.h' header once directly in its lx_emul compilation unit. The lx_kit interface files are only included in those compilation units that use or implement the interface. If a driver wants to use a generic implementation it must add the source file to its source file list. The generic implementations are located in _repos/dde_linux/src/lx_kit/_. The modular lx_kit still depends on the private _lx_emul.h_ header file that is tailored to each driver. Since the lx_kit already contains much of the declarations and definitions that were originally placed in these private header files, those files can now ommit a large amount of code. Fixes #1974.
67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
/*
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* \brief Slab allocator using our back-end allocator
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* \author Sebastian Sumpf
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* \author Josef Soentgen
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* \author Norman Feske
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* \date 2014-10-10
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*/
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/*
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* Copyright (C) 2014 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 _LX_KIT__INTERAL__SLAB_ALLOC_H_
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#define _LX_KIT__INTERAL__SLAB_ALLOC_H_
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/* Genode includes */
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#include <base/slab.h>
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#include <util/misc_math.h>
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/* Linux emulation environment includes */
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#include <lx_kit/internal/slab_backend_alloc.h>
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#include <lx_kit/types.h>
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namespace Lx { class Slab_alloc; }
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class Lx::Slab_alloc : public Genode::Slab
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{
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private:
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size_t const _object_size;
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/*
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* Each slab block in the slab contains about 8 objects (slab entries)
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* as proposed in the paper by Bonwick and block sizes are multiples of
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* page size.
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*/
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static size_t _calculate_block_size(size_t object_size)
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{
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size_t block_size = 16*object_size;
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return Genode::align_addr(block_size, 12);
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}
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public:
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Slab_alloc(size_t object_size, Slab_backend_alloc &allocator)
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:
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Slab(object_size, _calculate_block_size(object_size), 0, &allocator),
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_object_size(object_size)
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{ }
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Genode::addr_t alloc()
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{
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Genode::addr_t result;
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return (Slab::alloc(_object_size, (void **)&result) ? result : 0);
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}
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void free(void *ptr)
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{
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Slab::free(ptr, _object_size);
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}
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};
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#endif /* _LX_KIT__INTERAL__SLAB_ALLOC_H_ */
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