On Wed, 2014-05-07 at 10:09 +0800, Xuebing Wang wrote:
On 05/04/2014 07:33 PM, Jeroen Hofstee wrote:
Hello Xuebing, (freebsd-arm added on cc),
On di, 2014-04-08 at 16:52 +0800, Xuebing Wang wrote:
Hi u-boot community,
I am trying to port u-boot (release u-boot-2014.04-rc3.tar.bz2) to FreeBSD on BeagleBone Black.
In FreeBSD, there is a u-boot loader (named ubldr), which can call u-boot API to get fdt (Flat Device Tree) data.
I have to comment out below 3 lines, in order to get correct fdt data in FreeBSD ubldr from u-boot. Would you please advice what is the best way to fix this?
In file common/env_common.c: const uchar *env_get_addr(int index) { // if (gd->env_valid) // return (uchar *)(gd->env_addr + index); // else return &default_environment[index]; }
Assuming that you checked that your environment is valid you might be facing the fact that the gd pointer is corrupted. gd is a pointer to the "global data" and used for storing globals which are available before and after relocation. On (32bit) ARM this value used to be stored in register r8 but moved to r9 (llvm cannot reserve an arbitrary register, but can reserve r9 for platform specific usage). If ubldr uses r9 you end up with a invalid gd pointer when calling back into u-boot. ubldr now reserves r8 and r9 so a recent version should work fine on an older U-boot as well as current master.
Can you check the latest ubldr?
Hi Jeroen,
Thanks for your response.
- Today, I tested ubldr in the snapshot build
FreeBSD-11.0-CURRENT-arm-armv6-BEAGLEBONE-20140428-r265054.img.bz2 without commenting out those 3 lines, I still can not get "fdt ls" in ubldr command line.
After commenting out those 3 lines and rebuild u-boot, I can get "fdt ls" in ubldr command line.
Note: All my previous test was based on FreeBSD-11.0-CURRENT-arm-armv6-BEAGLEBONE-20140323-r263665.img.bz2
- Would you please point to me which revision that reserves both r8 and r9?
Thanks.
Regards, Jeroen
I think you should be debugging this from the ubldr side. If 'fdt ls' fails to load the dtb when the u-boot global env is present, then what we need to know is what result is being returned when ubldr looks up the fdtaddr and/or fdt_addr variables. Does it get an address for the dtb at all? Is the address invalid? Is it valid but it points to something that doesn't look like a valid dtb header?
-- Ian