Date: Wed, 07 May 2014 10:09:19 +0800 From: Xuebing Wang <xbing6@gmail.com> To: Jeroen Hofstee <dasuboot@myspectrum.nl> Cc: trini@ti.com, u-boot@lists.denx.de, vanbaren@cideas.com, freebsd-arm@freebsd.org Subject: Re: [U-Boot] Latest u-boot release on BeagleBone Black for FreeBSD Message-ID: <536995CF.4060404@gmail.com> In-Reply-To: <1399203211.1994.25.camel@yellow> References: <5343B8B9.6040607@gmail.com> <1399203211.1994.25.camel@yellow>
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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.
1) 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
2) Would you please point to me which revision that reserves both r8 and r9?
Thanks.
> Regards,
> Jeroen
>
>
>
--
Thanks,
Xuebing Wang
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