[U-Boot] [PATCH 6/7] arm: ls102xa: Add SD boot support for LS1021AQDS board

[Albert ARIBAUD]

Hi Huan,

On Thu, 25 Sep 2014 06:45:00 +0000, Huan Wang
<alison.wang at freescale.com> wrote:

> Hi, Albert,
> 
> > On Mon, 22 Sep 2014 06:46:20 +0000, Huan Wang
> > <alison.wang at freescale.com> wrote:
> > 
> > > Hi, Albert,
> > >
> > > > > On Thu, 18 Sep 2014 13:47:18 +0800, Alison Wang
> > > > > <b18965 at freescale.com>
> > > > > wrote:
> > > > >
> > > > > > +
> > > > > > +     . = ALIGN(4);
> > > > > > +     .u_boot_list : {
> > > > > > +             KEEP(*(SORT(.u_boot_list*_i2c_*)));
> > > > > > +     }
> > > > >
> > > > > IS this required? And if it is, could it not be added to the
> > > > > arch/arm/cpu/u-boot-spl.lds file? This way you would not need an
> > > > > .lds file at all.
> > > > >
> > > > > [Alison Wang] Yes, it is required.
> > > >
> > > > Ok -- what for? :)
> > > [Alison Wang] In SPL part, DDR is initialized by reading SPD through
> > I2C interface.
> > > For I2C, ll_entry_count() is called, and it returns the number of
> > > elements of a linker-generated array placed into subsection of
> > > .u_boot_list section specified by _list argument. So I need to add
> > this to make I2C work in SPL.
> > 
> > Understood. So your SPL code uses I2C, and for I2C, you need a linker
> > list. But then:
> > 
> > > > > I would like to add it in arch/arm/cpu/u-boot-spl.lds. I was not
> > > > > sure adding it in arch/arm/cpu/u-boot-spl.lds is acceptable or
> > not.
> > > >
> > > > (assuming the reason why it is needed is valid) If it causes no
> > > > change to boards which do not use it right now (and I mean 'no
> > > > change' ad 'binary identical') then this is acceptable. Make sure
> > > > you check the binary invariance and that you mention it in the
> > commit.
> > > >
> > > [Alison Wang] It will cause the binary is not identical for other
> > board.
> > 
> > Is this a prediction or an actual observation of compared builds with
> > and without the I2C linker liste addition to the generic SPL .lds?
> 
> [Alison Wang] I use mx31pdk as example. I compared the binaries with and
> Without the I2C linker list in arch/arm/cpu/u-boot-spl.lds. The binaries
> are not identical.

I have just checked mx31pdk: the u-boot binaries (u-boot, u-boot.bin,
u-boot-with-spl.bin, u-boot.map, u-boot.srec) are indeed different, but
that's just normal considering the repository state and build date and
time are included in the binaries [1].

OTOH, I see that the u-boot-spl.bin files are identical.

The only change I made between the two builds was inserting

	>         . = ALIGN(4);
	> +       .u_boot_list : {
	> +               KEEP(*(SORT(.u_boot_list*_i2c_*)));
	> +       }  

in arch/arm/cpu/u-boot-spl.lds at line 34.

Can you re-check?

> Best Regards,
> Alison Wang

[1] BTW, how do you folks out here proceed when trying to compare
u-boot.bin files from different builds of the same target without
the repo state or build date and time affecting the comparison? I use a
patch to Makefile that fakes the commit and repo state, and I also use
fakelib to force timestamps, but there might be a simpler way.

Amicalement,
-- 
Albert.