On 9/21/20 7:43 PM, André Przywara wrote:
On 03/09/2020 06:07, Samuel Holland wrote:
Hi,
Previously, fdtfile was always the value in CONFIG_DEFAULT_DEVICE_TREE. This meant that, regardless of the DT chosen by SPL (either by changing the header in the image or by the selection code at runtime), Linux always used the default DT.
By using the name from the SPL header (which, because of the previous commit, always matches the DT used by U-Boot proper), Linux also sees the same board as U-Boot/SPL, even if the boot script later loads a DT from disk.
I strongly frown upon proliferating the broken way of explicitly loading a DT from somewhere, when the DT embedded in U-Boot should be all we will ever need.
The embedded DT is only "all you ever need" if 1) your DT is 100% complete and accurate (ha, ha, ha) or 2) you re-flash U-Boot every time the device tree changes, which is risky and an unnecessary waste of flash memory write cycles.
Having a built-in DT that's always available and mostly works is quite useful, but complaining that distros and users want to update their DTs without patching, recompiling, and re-flashing U-Boot is frankly ridiculous. Especially considering that the U-Boot DTs are usually out of date, and users might not want to update the U-Boot code for various reasons.
But making the selected DT available to U-Boot scripts doesn't really hurt or prevent us from doing it properly, so:
Signed-off-by: Samuel Holland samuel@sholland.org
One nit below, with that: Reviewed-by: Andre Przywara andre.przywara@arm.com
Cheers, Andre
board/sunxi/board.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/board/sunxi/board.c b/board/sunxi/board.c index eaa40a1ea96..5457b28e135 100644 --- a/board/sunxi/board.c +++ b/board/sunxi/board.c @@ -870,6 +870,7 @@ static void setup_environment(const void *fdt)
int misc_init_r(void) {
const char *spl_dt_name; uint boot;
env_set("fel_booted", NULL);
@@ -888,6 +889,16 @@ int misc_init_r(void) env_set("mmc_bootdev", "1"); }
- /* Set fdtfile to match the FIT configuration chosen in SPL. */
- spl_dt_name = get_spl_dt_name();
- if (spl_dt_name) {
char *prefix = IS_ENABLED(CONFIG_ARM64) ? "allwinner/" : "";char str[64];The longest name (including the directory name) is 49 characters so far, so let's hope that people don't go crazy with their DT names. Shall we check the return value of snprintf() and at least complain? In contrast to strncpy(), snprintf() is safe, but might still truncate the name.
What kind of complaint were you thinking of? Trying to actually use a truncated $fdtfile would produce a "file not found" error. Maybe that would be obvious enough?
Cheers, Samuel
Cheers, Andre.
snprintf(str, sizeof(str), "%s%s.dtb", prefix, spl_dt_name);env_set("fdtfile", str);- }
- setup_environment(gd->fdt_blob);
#ifdef CONFIG_USB_ETHER