[U-Boot] Prefetch abort exception

[U-Boot] Prefetch abort exception

[Parimala Baggiri]

Hello,

I have added interrupt support for armv7 platform, by implementing the
do_irq and irq_install_handler and arch_interrupt_init functions.

Initially default_isr is the handler function installed for all the
interrupts.

[U-Boot] Prefetch abort exception

[Albert ARIBAUD]

Hi Parimala,

On Mon, 13 Jan 2014 19:00:04 +0530, Parimala Baggiri
<baggiriparimala@gmail.com> wrote:

> Hello,
> 
> I have added interrupt support for armv7 platform, by implementing the
> do_irq and irq_install_handler and arch_interrupt_init functions.
> 
> Initially default_isr is the handler function installed for all the
> interrupts.
> 
> From my standalone application, I am enabling the interrupts and installing
> the handler to be called for my peripheral interrupt.
> 
> If I don't install my handler, U-Boot executes default_isr successfully.
> 
> If I use my handler, when the interrupt occurs I am getting the prefetch
> abort exception with the following dump
> prefetch abort
> pc : [<ebd78002>]          lr : [<bff8f720>]
> sp : bfeef200  ip : bfeef358     fp : bfef1d48
> r10: bfef1d78  r9 : 00000002     r8 : bfeeff58
> r7 : bffac284  r6 : 60000153     r5 : bffbb5c0  r4 : 00000000
> r3 : bffab29c  r2 : 00000000     r1 : 000003e8  r0 : 8500178c
> Flags: nZCv  IRQs off  FIQs off  Mode IRQ_32
> Resetting CPU ...
> 
> resetting ...
> 
> U-Boot SPL 2013.01.-rc1-00003-g43ee87a-dirty (Jan 10 2014 - 16:04:35)
> OMAP4460 ES1.1
> OMAP SD/MMC: 0
> reading u-boot.img
> reading u-boot.img
> 
> Can any one please help me to solve this?

You're the best suited to tell, since you're the only one who can read
or test the code, so the following question is just a wild guess: does
the interrupt handler properly save (and restore) the interrupted
context, and does it properly establish (and dispose of) its own
context?
 
Amicalement,
-- 
Albert.

[U-Boot] Prefetch abort exception

[Parimala Baggiri]

Hello,

On Tue, Jan 14, 2014 at 11:30 AM, Albert ARIBAUD
<albert.u.boot@aribaud.net>wrote:

> Hi Parimala,
>
> On Mon, 13 Jan 2014 19:00:04 +0530, Parimala Baggiri
> <baggiriparimala@gmail.com> wrote:
>
> > Hello,
> >
> > I have added interrupt support for armv7 platform, by implementing the
> > do_irq and irq_install_handler and arch_interrupt_init functions.
> >
> > Initially default_isr is the handler function installed for all the
> > interrupts.
> >
> > From my standalone application, I am enabling the interrupts and
> installing
> > the handler to be called for my peripheral interrupt.
> >
> > If I don't install my handler, U-Boot executes default_isr successfully.
> >
> > If I use my handler, when the interrupt occurs I am getting the prefetch
> > abort exception with the following dump
> > prefetch abort
> > pc : [<ebd78002>]          lr : [<bff8f720>]
> > sp : bfeef200  ip : bfeef358     fp : bfef1d48
> > r10: bfef1d78  r9 : 00000002     r8 : bfeeff58
> > r7 : bffac284  r6 : 60000153     r5 : bffbb5c0  r4 : 00000000
> > r3 : bffab29c  r2 : 00000000     r1 : 000003e8  r0 : 8500178c
> > Flags: nZCv  IRQs off  FIQs off  Mode IRQ_32
> > Resetting CPU ...
> >
> > resetting ...
> >
> > U-Boot SPL 2013.01.-rc1-00003-g43ee87a-dirty (Jan 10 2014 - 16:04:35)
> > OMAP4460 ES1.1
> > OMAP SD/MMC: 0
> > reading u-boot.img
> > reading u-boot.img
> >
> > Can any one please help me to solve this?
>
> You're the best suited to tell, since you're the only one who can read
> or test the code, so the following question is just a wild guess: does
> the interrupt handler properly save (and restore) the interrupted
> context, and does it properly establish (and dispose of) its own
> context?
>
> Thank you all for the suggestions
I found that, using "printf" statement within my ISR is causing the
prefetch abort.

Regards,
Parimala

[U-Boot] Prefetch abort exception

[Albert ARIBAUD]

Hi Parimala,

On Thu, 16 Jan 2014 17:55:10 +0530, Parimala Baggiri
<baggiriparimala@gmail.com> wrote:

> Hello,
> 
> On Tue, Jan 14, 2014 at 11:30 AM, Albert ARIBAUD
> <albert.u.boot@aribaud.net>wrote:
> 
> > Hi Parimala,
> >
> > On Mon, 13 Jan 2014 19:00:04 +0530, Parimala Baggiri
> > <baggiriparimala@gmail.com> wrote:
> >
> > > Hello,
> > >
> > > I have added interrupt support for armv7 platform, by implementing the
> > > do_irq and irq_install_handler and arch_interrupt_init functions.
> > >
> > > Initially default_isr is the handler function installed for all the
> > > interrupts.
> > >
> > > From my standalone application, I am enabling the interrupts and
> > installing
> > > the handler to be called for my peripheral interrupt.
> > >
> > > If I don't install my handler, U-Boot executes default_isr successfully.
> > >
> > > If I use my handler, when the interrupt occurs I am getting the prefetch
> > > abort exception with the following dump
> > > prefetch abort
> > > pc : [<ebd78002>]          lr : [<bff8f720>]
> > > sp : bfeef200  ip : bfeef358     fp : bfef1d48
> > > r10: bfef1d78  r9 : 00000002     r8 : bfeeff58
> > > r7 : bffac284  r6 : 60000153     r5 : bffbb5c0  r4 : 00000000
> > > r3 : bffab29c  r2 : 00000000     r1 : 000003e8  r0 : 8500178c
> > > Flags: nZCv  IRQs off  FIQs off  Mode IRQ_32
> > > Resetting CPU ...
> > >
> > > resetting ...
> > >
> > > U-Boot SPL 2013.01.-rc1-00003-g43ee87a-dirty (Jan 10 2014 - 16:04:35)
> > > OMAP4460 ES1.1
> > > OMAP SD/MMC: 0
> > > reading u-boot.img
> > > reading u-boot.img
> > >
> > > Can any one please help me to solve this?
> >
> > You're the best suited to tell, since you're the only one who can read
> > or test the code, so the following question is just a wild guess: does
> > the interrupt handler properly save (and restore) the interrupted
> > context, and does it properly establish (and dispose of) its own
> > context?
> >
> > Thank you all for the suggestions
> I found that, using "printf" statement within my ISR is causing the
> prefetch abort.

Well, it usually isn't a good idea to try and use such functions as
printf() within an interrupt handler, if only because you might have
interrupted a call to printf(), and printf() might not be re-entrant,
which could explain the abort you see.

Besides, even with a re-entrant printf() implementation, interrupting
printf() to do a printf() will propably result in mangled output.

> Regards,
> Parimala

Amicalement,
-- 
Albert.