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author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2010-09-08 17:38:44 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2010-09-08 17:38:44 +0000 |
commit | f5072951cc0ddc165fea568a2733a19b51ed1cee (patch) | |
tree | ce666d30296334e7635272e8f80c442dd11117bb /nuttx/configs/ea3131/README.txt | |
parent | 7aef1347d64241b4516a32aeb7dd7f9696aa75b4 (diff) | |
download | px4-nuttx-f5072951cc0ddc165fea568a2733a19b51ed1cee.tar.gz px4-nuttx-f5072951cc0ddc165fea568a2733a19b51ed1cee.tar.bz2 px4-nuttx-f5072951cc0ddc165fea568a2733a19b51ed1cee.zip |
Implement SD-based paging for EA3131
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2931 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/configs/ea3131/README.txt')
-rwxr-xr-x | nuttx/configs/ea3131/README.txt | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/nuttx/configs/ea3131/README.txt b/nuttx/configs/ea3131/README.txt index 2e3c1b874..556c4cb25 100755 --- a/nuttx/configs/ea3131/README.txt +++ b/nuttx/configs/ea3131/README.txt @@ -416,8 +416,41 @@ On-Demand Paging The references and issues related to this are discussed in (2) and (3) above. + Alternative: + ------------ + + I have implemented an alternative within configs/ea3131/src/up_fillpage.c + which is probably only useful for testing. Here is the usage module + for this alternative + + 1. Place the nuttx.bin file on an SD card. + 2. Insert the SD card prior to booting + 3. In up_fillpage(), use the virtual miss address (minus the virtual + base address) as an offset into the nuttx.bin file, and read the + required page from that offset in the nuttx.bin file: + + off_t offset = (off_t)vpage - PG_LOCKED_VBASE; + off_t pos = lseek(fd, offset, SEEK_SET); + if (pos != (off_t)-1) + { + int ret = read(fd, vpage, PAGESIZE); + } + + In this way, the paging implementation can do on-demand paging + from an image file on the SD card. Problems/issues with this + approach probably make it only useful for testing: + + 1. You would still have to boot the locked section over serial or + using a bootloader -- it is not clear how the power up boot + would occur. For testing, the nuttx.bin file could be both + provided on the SD card and loaded over serial. + 2. If the SD card is not in place, the system will crash. + 3. This means that all of the file system logic and FAT file + system would have to reside in the locked text region. + ARM/EA3131-specific Configuration Options ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + CONFIG_ARCH - Identifies the arch/ subdirectory. This should be set to: @@ -500,7 +533,7 @@ ARM/EA3131-specific Configuration Options CONFIG_LPC313X_MCI, CONFIG_LPC313X_SPI, CONFIG_LPC313X_UART - xernal memory available on the board (see also CONFIG_MM_REGIONS) + External memory available on the board (see also CONFIG_MM_REGIONS) CONFIG_LPC313X_EXTSRAM0 - Select if external SRAM0 is present CONFIG_LPC313X_EXTSRAM0HEAP - Select if external SRAM0 should be |