On Tue, May 24, 2016 at 8:55 PM, Robert P. J. Day rpjday@crashcourse.ca wrote:

looking at the code for fdt_fixup_ethernet() in fdt_support.c, and i'm puzzled by the extra work being done ostensibly to take an "edited" FDT into account:

void fdt_fixup_ethernet(void *fdt) { int i, j, prop; char *tmp, *end; char mac[16]; const char *path; unsigned char mac_addr[6]; int offset;

    if (fdt_path_offset(fdt, "/aliases") < 0)
            return;

    /* Cycle through all aliases */
    for (prop = 0; ; prop++) {
            const char *name;
            int len = strlen("ethernet");

            /* FDT might have been edited, recompute the offset */
            offset = fdt_first_property_offset(fdt,
                    fdt_path_offset(fdt, "/aliases"));
            /* Select property number 'prop' */
            for (i = 0; i < prop; i++)
                    offset = fdt_next_property_offset(fdt, offset);
            ... snip ...

why is it that *this* routine has to worry about an edited FDT, but nothing else i see in that entire source file has to? as a (hopefully) relevant example:

#if defined(OF_STDOUT_PATH) static int fdt_fixup_stdout(void *fdt, int chosenoff) { return fdt_setprop(fdt, chosenoff, "linux,stdout-path", OF_STDOUT_PATH, strlen(OF_STDOUT_PATH) + 1); }

that routine simply calls fdt_setprop() ... what is it about fdt_fixup_ethernet() that needs to take extra care compared to every other function in that file?

Commit a434fd1d282fd32d81296c6d4c2e0911f6e488b3 explains this.

Regards, Bin