On Fri, 23 Aug 2013, Stefano Babic wrote:
Hi Robert,
On 23/08/2013 14:25, Robert P. J. Day wrote:
i'm sure there's a simple answer to this
There is
-- i built u-boot for my beaglebone black using the "am335x_boneblack" config, which supports saving env info to the eMMC HW partition boot1. but now that it's there, is there a way i can manipulate that info with fw_printenv and fw_setenv?
Check in code - fw_printenv / fw_setenv are supposed to work with a MTD device, and the MMC is not. There are some additional checks and handling of NOR and NAND devices is done differently. But there is no code for MMC.
yup, i can see that. the tools i was using were an earlier version selected by my OE build, where the code in fw_env.c was:
static int flash_read (int fd) { struct mtd_info_user mtdinfo; int rc;
rc = ioctl (fd, MEMGETINFO, &mtdinfo); if (rc < 0) { perror ("Cannot get MTD information"); <-- where it was failing return -1; }
if (mtdinfo.type != MTD_NORFLASH && mtdinfo.type != MTD_NANDFLASH && mtdinfo.type != MTD_DATAFLASH) { fprintf (stderr, "Unsupported flash type %u\n", mtdinfo.type); return -1; } ... snip ...
i can see, in the current repo, that's been refined to distinguish between block and character device files:
static int flash_read (int fd) { struct mtd_info_user mtdinfo; struct stat st; int rc;
rc = fstat(fd, &st); if (rc < 0) { fprintf(stderr, "Cannot stat the file %s\n", DEVNAME(dev_current)); return -1; }
if (S_ISCHR(st.st_mode)) { rc = ioctl(fd, MEMGETINFO, &mtdinfo); if (rc < 0) { fprintf(stderr, "Cannot get MTD information for %s\n", DEVNAME(dev_current)); return -1; } if (mtdinfo.type != MTD_NORFLASH && mtdinfo.type != MTD_NANDFLASH && mtdinfo.type != MTD_DATAFLASH && mtdinfo.type != MTD_UBIVOLUME) { fprintf (stderr, "Unsupported flash type %u on %s\n", mtdinfo.type, DEVNAME(dev_current)); return -1; } } else { memset(&mtdinfo, 0, sizeof(mtdinfo)); mtdinfo.type = MTD_ABSENT; } ... snip ...
which, as you point out, still doesn't solve the problem.
However, managing MMC is easier: no need of erasing flash, simply write into the device computing the CRC. You could add the required functions to rwad / write a buffer from MMC to fw_printenv (and posting here the patch, thanks !).
as i read it (and i could be totally wrong here), all that needs to be added is a way to specify to the fw_* tools that a given (block) partition has nothing to do with flash, and that it should be treated as pure data, bypassing any flash-related processing as you say.
i'm assuming that this would require deciding how to specify this in /etc/fw_env.config so the tools understand what's happening. thoughts on that? the line will look like:
/dev/mmcblk1boot1 ... and what goes here? ...
to identify this as a non-MTD partition?
and i guess that 16-character filename limit needs to be adjusted as well, yes?
rday