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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
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patacongo 2010-08-22 00:48:43 +00:00
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Documentation/NuttxPortingGuide.html
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@ -12,7 +12,7 @@
<h1><big><font color="#3c34ec">
<i>NuttX RTOS Porting Guide</i>
</font></big></h1>
<p>Last Updated: August 16, 2010</p>
<p>Last Updated: August 21, 2010</p>
</td>
</tr>
</table>
@ -2390,7 +2390,6 @@ extern void up_ledoff(int led);
If CONFIG_PAGING is selected, then the following also apply:
</p>
<ul>
</li>
<li>
<code>CONFIG_PAGING_PAGESIZE</code>:
The size of one managed page.
@ -2403,30 +2402,68 @@ extern void up_ledoff(int led);
(<code>CONFIG_DRAM_VSTART</code> + <code>CONFIG_PAGING_PAGESIZE</code>*<code>CONFIG_PAGING_NLOCKED</code>)
</li>
<li>
<code>CONFIG_PAGING_NPAGES</code>:
The number of pages in the paged region of the memory map.
This paged region then begins at
(<code>CONFIG_DRAM_VSTART</code> + <code>CONFIG_PAGING_PAGESIZE</code>*<code>CONFIG_PAGING_NLOCKED</code>)
and continues until (<code>CONFIG_DRAM_VSTART</code> +
<code>CONFIG_PAGING_PAGESIZE</code>*(<code>CONFIG_PAGING_NLOCKED</code> + <code>CONFIG_PAGING_NPAGES</code>)
<code>CONFIG_PAGING_LOCKED_PBASE</code> and <code>CONFIG_PAGING_LOCKED_VBASE</code>:
These may be defined to determine the base address of the locked page regions.
If neither are defined, the logic will be set the bases to <code>CONFIG_DRAM_START</code>
and <code>CONFIG_DRAM_VSTART</code> (i.e., it assumes that the base address of the locked
region is at the beginning of RAM).
<b>NOTE</b>:
In some architectures, it may be necessary to take some memory from the beginning
of this region for vectors or for a page table.
In such cases, <code>CONFIG_PAGING_LOCKED_P/VBASE</code> should take that into consideration
to prevent overlapping the locked memory region and the system data at the beginning of SRAM.
</li>
<li>
<code>CONFIG_PAGING_NPPAGED</code>:
This is the number of physical pages available to support the paged text region.
This paged region begins at
(<code>CONFIG_PAGING_LOCKED_PBASE</code> + <code>CONFIG_PAGING_PAGESIZE</code>*<code>CONFIG_PAGING_NPPAGED</code>)
and continues until
(<code>CONFIG_PAGING_LOCKED_PBASE</code> + <code>CONFIG_PAGING_PAGESIZE</code>*(<code>CONFIG_PAGING_NLOCKED</code> +
<code>CONFIG_PAGING_NPPAGED</code>)
</li>
<li>
<code>CONFIG_PAGING_NVPAGED</code>:
This actual size of the paged text region (in pages).
This is also the number of virtual pages required to support 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?
</li>
<li>
<code>CONFIG_PAGING_NDATA</code>:
This is the number of data pages in the memory map.
The data region will extend to the end of RAM unless overridden by a setting in the configuration file.
<b>NOTE</b>:
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:
<code>CONFIG_PAGING_NDATA</code> should be defined to prevent the data region from extending all the way to the end of memory.
</li>
<li>
<code>CONFIG_PAGING_DEFPRIO</code>:
The default, minimum priority of the page fill worker thread.
The priority of the page fill work thread will be boosted boosted dynmically so that it matches the priority of the task on behalf of which it peforms the fill.
This defines the minimum priority that will be used.
Default: 50.
The priority of the page fill work thread will be boosted boosted dynmically so that it matches the
priority of the task on behalf of which it peforms the fill.
This defines the minimum priority that will be used. Default: 50.
</li>
<li>
<code>CONFIG_PAGING_STACKSIZE </code>:
Defines the size of the allocated stack for the page fill worker thread.
Default: 1024.
<code>CONFIG_PAGING_STACKSIZE</code>:
Defines the size of the allocated stack for the page fill worker thread. Default: 1024.
</li>
<li>
<code>CONFIG_PAGING_BLOCKINGFILL</code>:
The architecture specific <code>up_fillpage()</code> function may be blocking or non-blocking.
If defined, this setting indicates that the <code>up_fillpage()</code> implementation will block until the transfer is completed.
Default: Undefined (non-blocking).
If defined, this setting indicates that the <code>up_fillpage()</code> implementation will block until the
transfer is completed. Default: Undefined (non-blocking).
</li>
<li>
<code>CONFIG_PAGING_WORKPERIOD</code>:
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 <code>CONFIG_PAGING_TIMEOUT_TICKS</code>).
</li>
<li>
<code>CONFIG_PAGING_TIMEOUT_TICKS</code>:
@ -2434,6 +2471,23 @@ extern void up_ledoff(int led);
If the fill takes longer than this number if microseconds, then a fatal error will be declared.
Default: No timeouts monitored.
</li>
<p>
Some architecture-specific settings.
Defaults are architecture specific.
If you don't know what you are doing, it is best to leave these undefined and try the system defaults:
</p>
<li>
<code>CONFIG_PAGING_VECPPAGE</code>:
This the physical address of the page in memory to be mapped to the vector address.
</li>
<li>
<code>CONFIG_PAGING_VECL2PADDR</code>:
This is the physical address of the L2 page table entry to use for the vector mapping.
</li>
<li>
<code>CONFIG_PAGING_VECL2VADDR</code>:
This is the virtual address of the L2 page table entry to use for the vector mapping.
</li>
</ul>
<p>
The following can be used to disable categories of APIs supported