[PATCH] GSoC: Cache configurations Raspberry Pi 2 support

[Rohini Kulkarni]

On Fri, Jul 24, 2015 at 7:03 PM, Gedare Bloom <gedare at gwu.edu> wrote:

> On Fri, Jul 24, 2015 at 3:30 AM, Rohini Kulkarni <krohini1593 at gmail.com>
> wrote:
> > On 24 Jul 2015 12:35, "Sebastian Huber" <
> sebastian.huber at embedded-brains.de>
> > wrote:
> >>
> >>
> >>
> >> On 23/07/15 23:24, Rohini Kulkarni wrote:
> >>>
> >>> I could finally get back to this issue. I used Pi 1 for debugging, but
> >>> the reason for this problem will apply to Pi 2 also.
> >>> With text section set to ARMV7_MMU_CODE_CACHED ( which implies read
> only)
> >>> , a data abort exception occurs with memset() inside
> bsp_start_clear_bss()
> >>> function. An illegal write access to an address according to me.
> >>
> >>
> >> Which exception and which address? Something is not working here.
> >
> >
> > This is a part of the debugging output. When I used
> ARMV7_MMU_CODE_CACHED.
> > (gdb) s
> > bsp_start_clear_bss ()
> >     at ../../../../../.././raspberrypi/lib/include/bsp/start.h:126
> > 126      memset(bsp_section_bss_begin, 0, (size_t) bsp_section_bss_size);
> What are the values of bsp_section_bss_begin, and bsp_section_bss_size?
>
> Apparently, the memset is trying to write into the .text (code)
> section, which is a very bad thing to do indeed.
>
> > (gdb) s
> > memset (m=0x1157e0, c=0, n=64176)
>

These memset parameters indicate the start location bsp_section_bss_begin
and size of bss section bsp_section_bss_size.


>     at ../../../../../gcc-4.9.2/newlib/libc/string/memset.c:59
> > 59    ../../../../../gcc-4.9.2/newlib/libc/string/memset.c: No such file
> or
> > directory.
> > (gdb) s
> > 49    in ../../../../../gcc-4.9.2/newlib/libc/string/memset.c
> > (gdb) s
> > _ARMV4_Exception_data_abort_default ()
> >     at
> >
> ../../../../../../../../rtems-local/rtems/c/src/../../cpukit/score/cpu/arm/armv4-exception-default.S:71
> > 71        sub    sp, #MORE_CONTEXT_SIZE
> >
> > When I set text section flag to ARMV7_MMU_READ_WRITE, the system starts
> > successfully.
> >>
> >>
> >> --
> >> Sebastian Huber, embedded brains GmbH
> >>
> >> Address : Dornierstr. 4, D-82178 Puchheim, Germany
> >> Phone   : +49 89 189 47 41-16
> >> Fax     : +49 89 189 47 41-09
> >> E-Mail  : sebastian.huber at embedded-brains.de
> >> PGP     : Public key available on request.
> >>
> >> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
> >>
> >
> > _______________________________________________
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
>



-- 
Rohini Kulkarni
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