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--- documentation:memory_allocation [2006/05/02 15:40]
+++ documentation:memory_allocation [2006/05/02 15:40] (current)
@@ Line 1: / Line 1: @@
+===== Basics =====
+For different tasks it is necessary to allocate a chunk of memory. Especially in the Linux kernel, stack space is pretty tight, so you quite often cannot simply declare some large variable and hope it works out.
+The usual way to allocate kernel memory is using kmalloc/kfree for rather small amounts (allocated continuously as real memory) and vmalloc/vfree (virtual memory) for large sizes. Unfortunately, you have to find out yourself, which method is better. kmalloc will fail, if you try to allocate more than 128M - anyway, continous memory of several pages might be difficult to get.
+===== RSBAC memory allocation =====
+RSBAC provides some own memory management functions. These functions also get exported for modules, if REG support has been enabled.
+In kernel versions from 2.4.0, separate RSBAC memory slabs are used for kmalloc style memory to provide better control of memory usage through /proc/slabinfo.
+  * All functions are defined here:
+<code c>#include <rsbac/rkmem.h></code>
+  * rsbac_kmalloc works like kmalloc with second parameter GFP_KERNEL.
+<code c>void * rsbac_kmalloc (size_t size);</code>
+  * rsbac_kfree is used like kfree - please make sure you do not call it with wrong pointers
+<code c>void rsbac_kfree (const void *objp);</code>
+  * rsbac_vkmalloc allocates via rsbac_kmalloc for small sizes (up to RSBAC_MAX_KMALLOC) and via vmalloc for larger sizes. Whether vmalloc has been used is put into *vmalloc_used_p as boolean value TRUE or FALSE
+<code c>void * rsbac_vkmalloc
+ (size_t size, boolean * vmalloc_used_p);</code>
+  * rsbac_vkfree is used to free such memory. To know the memory type, it needs the boolean value vmalloc_used from rsbac_vkmalloc
+<code c>void rsbac_vkfree (void *objp, boolean vmalloc_used);</code>

//