179 lines
5.2 KiB
Plaintext
179 lines
5.2 KiB
Plaintext
apps/system/zoneinfo/README.txt
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Author: Gregory Nutt <gnutt@nuttx.org>
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Directory Contents
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==================
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This directory contains logic to create a version of the TZ/Olson database.
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This database is required if localtime() support is selected via
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CONFIG_LIBC_LOCALTIME. This logic in this directory does the following:
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- It downloads the current TZ database from the IANA website
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- It downloads the current timezone tools from the same location
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- It builds the tools and constructs the binary TZ database
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- It will then, optionally, build a ROMFS filesystem image containing
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the data base.
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Creating and Mounting a ROMFS TZ Database
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=========================================
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The ROMFS filesystem image can that be mounted during the boot-up sequence
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so that it is available for the localtime() logic. There are two steps to
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doing this:
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- First, a ROM disk device must be created. This is done by calling
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the function romdisk_register() as described in
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nuttx/include/nuttx/drivers/ramdisk.h. This is an OS level operation
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and must be done in the board-level logic before your application
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starts.
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romdisk_register() will create a block driver at /dev/ramN where N
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is the device minor number that was provided to romdisk_regsiter.
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- The second step is to mount the file system. This step can be
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performed either in your board configuration logic or by your
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application using the mount() interface described in
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nuttx/include/sys/mount.h.
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These steps, however, must be done very early in initialization,
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before there is any need for time-related services.
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Both of these steps are shown together in the following code sample at the
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end of this README file.
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Example Configuration
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=====================
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I have tested this using the sim/nsh configuration. Here are the
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modifications to the configuration that I used for testing:
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CONFIG_BOARD_LATE_INITIALIZE=y
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CONFIG_LIBC_LOCALTIME=y
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CONFIG_LIBC_TZDIR="/share/zoneinfo"
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CONFIG_LIBC_TZ_MAX_TIMES=370
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CONFIG_LIBC_TZ_MAX_TYPES=20
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CONFIG_LIB_ZONEINFO=y
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CONFIG_LIB_ZONEINFO_ROMFS=y
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NOTE: The full TZ database is quite large. To create a reasonable sized
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ROMFS image, I had to trim some of the files like this:
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cd nuttx
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tools/configure.sh sim:nsh
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make menuconfig
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Select the above localtime() and nuttx/zoneinfo configuration settings.
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Then:
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make context
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cd ../nuttx/zoneinfo/tzbin/etc/zoneinfo
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Remove as many timezone files as you can. Do not remove the GMT, localtime,
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or posixrules files. Those might be needed in any event. Then you can
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force rebuilding of the ROMFS filesystem be removing some files:
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cd ../../..
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rm romfs_zoneinfo.*
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rm *.o
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cd ../../nuttx
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make
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If you have problems building the simulator on your platform, check out
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nuttx/boards/sim/sim/sim/README.txt. You might find some help there.
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Here is a sample run. I have not seen any errors in single stepping through
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the logic but neither am I certain that everything is working properly:
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NuttShell (NSH)
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nsh> date
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Jul 01 00:00:02 2008
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nsh> set TZ US/Mountain
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nsh> date -s "Apr 11 11:53:00 2015"
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nsh> date
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Apr 11 17:53:00 2015
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NOTE: Because of daylight savings time, US/Mountain is GMT-6 on Apr 11. The
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above suggests that perhaps the NSH data command may be setting local time,
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but printing GMT time?
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Sample Code to Mount the ROMFS Filesystem
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=========================================
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/mount.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <nuttx/drivers/ramdisk.h>
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#include <nuttx/zoneinfo.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#ifndef CONFIG_LIBC_TZDIR
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# error CONFIG_LIBC_TZDIR is not defined
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#endif
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#ifdef CONFIG_DISABLE_MOUNTPOINT
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# error "Mountpoint support is disabled"
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#endif
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#if CONFIG_NFILE_DESCRIPTORS < 4
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# error "Not enough file descriptors"
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#endif
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#ifndef CONFIG_FS_ROMFS
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# error "ROMFS support not enabled"
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#endif
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#define SECTORSIZE 64
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#define NSECTORS(b) (((b)+SECTORSIZE-1)/SECTORSIZE)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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int mount_zoneinfo(int minor)
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{
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char devname[32];
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int ret;
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/* Create a RAM disk for the test */
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ret = romdisk_register(minor, romfs_zoneinfo_img,
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NSECTORS(romfs_zoneinfo_img_len), SECTORSIZE);
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if (ret < 0)
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{
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printf("ERROR: Failed to create RAM disk\n");
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return ret;
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}
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/* Use the minor number to create a name for the ROM disk block device */
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snprintf(devname, 32, "/dev/ram%d", minor);
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/* Mount the ROMFS file system */
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printf("Mounting ROMFS filesystem at target=%s with source=%s\n",
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CONFIG_LIBC_TZDIR, devname);
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ret = mount(devname, CONFIG_LIBC_TZDIR, "romfs", MS_RDONLY, NULL);
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if (ret < 0)
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{
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printf("ERROR: Mount failed: %d\n", errno);
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return ret;
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}
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printf("TZ database mounted at %s\n", CONFIG_LIBC_TZDIR);
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return OK;
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}
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