[U-Boot] [PATCH 1/5] ARM: socfpga: Add boot trampoline for Arria10

[See, Chin Liang]

On Tue, 2018-04-17 at 11:28 +0200, Marek Vasut wrote:
> On 04/17/2018 11:11 AM, See, Chin Liang wrote:
> > 
> > On Tue, 2018-04-17 at 11:01 +0200, Marek Vasut wrote:
> > > 
> > > On 04/17/2018 10:52 AM, See, Chin Liang wrote:
> > > > 
> > > > 
> > > > On Tue, 2018-04-17 at 10:46 +0200, Marek Vasut wrote:
> > > > > 
> > > > > 
> > > > > On 04/17/2018 10:40 AM, See, Chin Liang wrote:
> > > > > > 
> > > > > > 
> > > > > > 
> > > > > > Hi Marek,
> > > > > > 
> > > > > > On Sun, 2018-04-15 at 15:37 +0200, Marek Vasut wrote:
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > The Arria10 uses slightly different boot image header
> > > > > > > than
> > > > > > > the
> > > > > > > Gen5
> > > > > > > SoCs,
> > > > > > > in particular the header itself contains an offset from
> > > > > > > the
> > > > > > > start
> > > > > > > of
> > > > > > > the
> > > > > > > header to which the Arria10 jumps. This offset must not
> > > > > > > be
> > > > > > > negative,
> > > > > > > yet
> > > > > > > the header is placed at offset 0x40 of the bootable
> > > > > > > binary.
> > > > > > > Therefore, to
> > > > > > > jump into U-Boot, add a trampoline just past the Arria10
> > > > > > > boot
> > > > > > > header
> > > > > > > and
> > > > > > > point to this trampoline at fixed offset from the header
> > > > > > > generated
> > > > > > > using
> > > > > > > the mkimage -T socfpgaimage_v1 . Note that it is not
> > > > > > > needed
> > > > > > > to
> > > > > > > jump
> > > > > > > back
> > > > > > > to offset 0x0 of the image, it is possible to jump
> > > > > > > directly
> > > > > > > at
> > > > > > > the
> > > > > > > reset
> > > > > > > label and save processing two instructions.
> > > > > > > 
> > > > > > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > > > > > Cc: Dinh Nguyen <dinguyen at kernel.org>
> > > > > > > Cc: Chin Liang See <chin.liang.see at intel.com>
> > > > > > > ---
> > > > > > >  arch/arm/mach-socfpga/include/mach/boot0.h | 4 ++--
> > > > > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > > > > > 
> > > > > > > diff --git a/arch/arm/mach-socfpga/include/mach/boot0.h
> > > > > > > b/arch/arm/mach-socfpga/include/mach/boot0.h
> > > > > > > index d6b9435d33..06bbe27d2c 100644
> > > > > > > --- a/arch/arm/mach-socfpga/include/mach/boot0.h
> > > > > > > +++ b/arch/arm/mach-socfpga/include/mach/boot0.h
> > > > > > > @@ -18,10 +18,10 @@ _start:
> > > > > > >  	.word	0xcafec0d3;	/* Checksum,
> > > > > > > zero-
> > > > > > > pad */
> > > > > > >  	nop;
> > > > > > >  
> > > > > > > -	b reset;		/* SoCFPGA jumps here */
> > > > > > > -	nop;
> > > > > > > +	b reset;		/* SoCFPGA Gen5 jumps
> > > > > > > here
> > > > > > > */
> > > > > > >  	nop;
> > > > > > >  	nop;
> > > > > > > +	b reset;		/* SoCFPGA Gen10
> > > > > > > trampoline
> > > > > > > */
> > > > > > Our mkpimage tools from SOCEDS is using 0x14 as offset.
> > > > > > Wonder
> > > > > > can
> > > > > > we
> > > > > > standardize that by using 0x14 instead of proposed 0x18 in
> > > > > > this
> > > > > > patch?
> > > > > What difference does it make, the entire image is generated
> > > > > during
> > > > > the
> > > > > build anyway ? This patch uses offset 0x1c, but what is the
> > > > > reason
> > > > > for
> > > > > address 0x14 in your proprietary tool, is there one ?
> > > > Our A10 header ended at 0x13 today. Hence we are continuing the
> > > > code at
> > > > 0x14 without any spacing.
> > > > 
> > > > While for 0x1c, should it be 3 nop?
> > > Yes, gives enough space were the header grow for whatever reason.
> > > Mind
> > > you, the NOPs are not executed, the socfpga jumps to 0x1c
> > > directly
> > > via
> > > 0x0c -- Image entry offset
> > Ok, I don't have strong objection on this. We can claim that we
> > don't
> > support use case where we use mkpimage tools from SCOEDS to sign
> > SPL
> > binary from mainstream.
> Which you can, why wouldn't it work ?
> 

Rethinking on this, yes as the nop shall able to handle this. Just the
vice versa won't work since downstream U-Boot already have the entry
fixed at 0x14.


> What is the benefit of using mkpimage if mkimage does the same thing
> though ?

Initial thought is for having both tools compatible. But rethinking the
makefile will handle this, we just advise user directly use sfp file
directly.

Thanks
Chin Liang