[U-Boot] question about TEXT_BASE in U-boot

[U-Boot] question about TEXT_BASE in U-boot

[王睿]

Hi everyone:

I am a freshman in U-boot development. My question to all expert is:

I set TEXT_BASE=0xA0f00000 in board/LPC2468OEM_Board/config.mk.

After compile, the first instruction is:
a0f00000: ea000014 b a0f00058 <reset>

However there is nothing at a0f00058 after power up board, so that
system hang up. (I download u-boot to ROM flash)

Can anyone explain that how u-boot boot after power up and what shall
I do to make u-boot work right?

Thanks very much.

[U-Boot] question about TEXT_BASE in U-boot

[wangrui]

Hi zhenhua:

After power up board, CPU will execute the instruction store at 0x0 (ROM
flash), and I download u-boot
to ROM flash (start from 0x0) so that the instruction store at 0x0 is 
"a0f00000: ea000014 b a0f00058 <reset>"

Then program will jump to 0xa0f00058 (SDRAM). However there shall be
nothing inSDRAM, because board
just powered up.

I wang to know how u-boot work after power up and TEXT_BASE is in SDRAM.
(My board is fresh and no bootloader in board)


On Sun, 2008-12-14 at 18:26 +0800, zhenhua lin wrote:
> >  However there is nothing at a0f00058 after power up board, so that
> system hang up. (I download u-boot to ROM flash)
> 
> Why? Do you change the map to relocate the callee? Please Check the
> callee whether  is it  at the right position.
> 
> 
> 
> 
> 
> 2008/12/14 ?? <wangr.bupt@gmail.com>:
> > Hi everyone:
> >
> > I am a freshman in U-boot development. My question to all expert is:
> >
> > I set TEXT_BASE=0xA0f00000 in board/LPC2468OEM_Board/config.mk.
> >
> > After compile, the first instruction is:
> > a0f00000: ea000014 b a0f00058 <reset>
> >
> > However there is nothing at a0f00058 after power up board, so that
> > system hang up. (I download u-boot to ROM flash)
> >
> > Can anyone explain that how u-boot boot after power up and what shall
> > I do to make u-boot work right?
> >
> > Thanks very much.
> >
> > _______________________________________________
> > U-Boot mailing list
> > U-Boot at lists.denx.de
> > http://lists.denx.de/mailman/listinfo/u-boot
> >
> >

[U-Boot] question about TEXT_BASE in U-boot

[tike64 at gmail.com]

wangrui wrote:
> After power up board, CPU will execute the instruction store at 0x0 (ROM
> flash), and I download u-boot
> to ROM flash (start from 0x0) so that the instruction store at 0x0 is 
> "a0f00000: ea000014 b a0f00058 <reset>"
> 
> Then program will jump to 0xa0f00058 (SDRAM)...

No, it does not. b is a relative branch and causes a jump to 0xa0f00058 
only if you execute it at 0xa0f00000. You would make yourself a big 
favor by familiarizing yourself with ARM instruction set.

--

Timo