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Update On-demand paging documentation

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2877 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo
2010-08-22 00:48:43 +00:00
parent 75b0f9d1ba
commit 0068ca76f4
6 changed files with 239 additions and 108 deletions
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include/nuttx/page.h
+15 -8
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@@ -85,10 +85,10 @@
#define PG_LOCKED_SIZE (CONFIG_PAGING_NLOCKED << PAGESHIFT)
/* CONFIG_PAGING_LOCKED_P/VBASE - May be defined to determine the base
* address of the locked page regions (lowest in memory). If both are not
* not defined, then this logic will be set to then to CONFIG_DRAM_START
* and CONFIG_DRAM_VSTART (i.e., assuming that the base address of the
* locked region is at the virtual address of the beginning of RAM).
* address of the locked page regions (lowest in memory). If neither
* are defined, then this logic will be set the bases to CONFIG_DRAM_START
* and CONFIG_DRAM_VSTART (i.e., it assumes that the base address of the
* locked region is at the beginning of RAM).
*
* NOTE: In some architectures, it may be necessary to take some memory
* from the beginning of this region for vectors or for a page table.
@@ -116,9 +116,10 @@
* support the paged text region.
* CONFIG_PAGING_NVPAGED - This actual size of the paged text region (in
* pages). This is also the number of virtual pages required to support
* the entire paged retion. This feature is intended to support only the
* case where the virtual paged text area is much larger the available
* physical pages. Otherwise, why would you being on-demand paging?
* the entire paged region. The on-demand paging feature is intended to
* support only the case where the virtual paged text area is much larger
* the available physical pages. Otherwise, why would you enable on-demand
* paging?
*/
#if CONFIG_PAGING_NPPAGED >= CONFIG_PAGING_NVPAGED
@@ -165,7 +166,7 @@
*
* NOTE: In some architectures, it may be necessary to take some memory
* from the end of RAM for page tables or other system usage. The
* configuration settings and linker directives must be cognizant of that.
* configuration settings and linker directives must be cognizant of that:
* CONFIG_PAGING_NDATA should be defined to prevent the data region from
* extending all the way to the end of memory.
*/
@@ -206,6 +207,12 @@
* function may be blocking or non-blocking. If defined, this setting
* indicates that the up_fillpage() implementation will block until the
* transfer is completed. Default: Undefined (non-blocking).
* CONFIG_PAGING_WORKPERIOD - The page fill worker thread will wake periodically
* even if there is no mapping to do. This selection controls that wake-up
* period (in microseconds). This wake-up a failsafe that will handle any
* cases where a single is lost (that would really be a bug and shouldn't
* happen!) and also supports timeouts for case of non-blocking, asynchronous
* fills (see CONFIG_PAGING_TIMEOUT_TICKS).
* CONFIG_PAGING_TIMEOUT_TICKS - If defined, the implementation will monitor
* the (asynchronous) page fill logic. If the fill takes longer than this
* number if microseconds, then a fatal error will be declared.