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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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configs/README.txt
+49 -7
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@@ -272,15 +272,40 @@ defconfig -- This is a configuration file similar to the Linux
CONFIG_PAGING_PAGESIZE - The size of one managed page. This must
be a value supported by the processor's memory management unit.
CONFIG_PAGING_NLOCKED - This is the number of locked pages in the
CONFIG_PAGING_NLOCKED - This is the number of locked pages in the
memory map. The locked address region will then be from
CONFIG_DRAM_VSTART through (CONFIG_DRAM_VSTART +
CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NLOCKED)
CONFIG_PAGING_NPAGES - The number of pages in the paged region of
the memory map. This paged region then begins at (CONFIG_DRAM_VSTART +
CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NLOCKED) and continues until
(CONFIG_DRAM_VSTART + CONFIG_PAGING_PAGESIZE*(CONFIG_PAGING_NLOCKED +
CONFIG_PAGING_NPAGES)
CONFIG_PAGING_LOCKED_PBASE and CONFIG_PAGING_LOCKED_VBASE - 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 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. In such cases, CONFIG_PAGING_LOCKED_P/VBASE should
take that into consideration to prevent overlapping the locked
memory region and the system data at the beginning of SRAM.
CONFIG_PAGING_NPPAGED - This is the number of physical pages
available to support the paged text region. This paged region
begins at (CONFIG_PAGING_LOCKED_PBASE + CONFIG_PAGING_PAGESIZE*CONFIG_PAGING_NPPAGED)
and continues until (CONFIG_PAGING_LOCKED_PBASE + CONFIG_PAGING_PAGESIZE*(CONFIG_PAGING_NLOCKED +
CONFIG_PAGING_NPPAGED)
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 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?
CONFIG_PAGING_NDATA - 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.
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:
CONFIG_PAGING_NDATA should be defined to prevent the data region from
extending all the way to the end of memory.
CONFIG_PAGING_DEFPRIO - 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
@@ -292,11 +317,28 @@ defconfig -- This is a configuration file similar to the Linux
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.
Default: No timeouts monitored.
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:
CONFIG_PAGING_VECPPAGE - This the physical address of the page in
memory to be mapped to the vector address.
CONFIG_PAGING_VECL2PADDR - This is the physical address of the L2
page table entry to use for the vector mapping.
CONFIG_PAGING_VECL2VADDR - This is the virtual address of the L2
page table entry to use for the vector mapping.
The following can be used to disable categories of APIs supported
by the OS. If the compiler supports weak functions, then it
should not be necessary to disable functions unless you want to
@@ -416,7 +458,7 @@ defconfig -- This is a configuration file similar to the Linux
CONFIG_NET - Enable or disable all network features
CONFIG_NET_IPv6 - Build in support for IPv6
CONFIG_NSOCKET_DESCRIPTORS - Maximum number of socket descriptors
per task/thread.
per task/thread.
CONFIG_NET_NACTIVESOCKETS - Maximum number of concurrent socket
operations (recv, send, etc.). Default: CONFIG_NET_TCP_CONNS+CONFIG_NET_UDP_CONNS
CONFIG_NET_SOCKOPTS - Enable or disable support for socket options