On Saturday 24 January 2015 00:48:55 Pavel Machek wrote:
> On Fri 2015-01-23 23:36:36, Pali Rohár wrote:
> > On Friday 23 January 2015 22:39:55 Pali Rohár wrote:
> > > Hello,
> > > 
> > > when I boot zImage with appended DT n900 in qemu
> > > fdt_open_into() function called from file
> > > arch/arm/boot/compressed/atags_to_fdt.c (in function
> > > atags_to_fdt) always returns -FDT_ERR_NOSPACE.
> > > 
> > > It means that all ATAGS (including cmdline arguments)
> > > passed by bootloader are ignored.
> > > 
> > > On real n900 device I see that booted DT version also
> > > ignore cmdline arguments from bootloader. I cannot debug
> > > decompress code on real device, but I think it is same
> > > problem as in qemu.
> > 
> > Looks like this quick patch is fixing above problem:
> So... something overruns stack, and bigger stack fixes it...?
> 
>                                                       Pavel
> 

Yes, it looks like that DTB file for n900 is too big and 
atags_to_fdt.c cannot append anything to it (kernel cmdline)...

> > diff --git a/arch/arm/boot/compressed/head.S
> > b/arch/arm/boot/compressed/head.S index 68be901..4a7d75b
> > 100644
> > --- a/arch/arm/boot/compressed/head.S
> > +++ b/arch/arm/boot/compressed/head.S
> > @@ -268,7 +268,7 @@ restart:        adr     r0, LC0
> > 
> >              * area.  No GOT fixup has occurred yet, but none of 
the
> >              * code we're about to call uses any global variable.
> >             
> >             */
> > 
> > -           add     sp, sp, #0x10000
> > +           add     sp, sp, #0x20000
> > 
> >             stmfd   sp!, {r0-r3, ip, lr}
> >             mov     r0, r8
> >             mov     r1, r6
> > 
> > @@ -289,7 +289,7 @@ restart:        adr     r0, LC0
> > 
> >             bleq    atags_to_fdt
> >             
> >             ldmfd   sp!, {r0-r3, ip, lr}
> > 
> > -           sub     sp, sp, #0x10000
> > +           sub     sp, sp, #0x20000
> > 
> >  #endif
> >  
> >             mov     r8, r6                  @ use the appended device tree

-- 
Pali Rohár
pali.ro...@gmail.com

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