* Access to first 0x1000 byte on imx53/imx6
@ 2015-01-29 9:12 Wjatscheslaw Stoljarski
2015-01-29 9:21 ` Sascha Hauer
0 siblings, 1 reply; 7+ messages in thread
From: Wjatscheslaw Stoljarski @ 2015-01-29 9:12 UTC (permalink / raw)
To: barebox
Hello,
If I try to read from first 4k RAM on imx53/imx6, with md or from code,
barebox show stacktrace with mesage:
"unable to handle NULL pointer dereference at address 0x...".
Is it possible in some way do that?
Thanks,
Slawa
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-29 9:12 Access to first 0x1000 byte on imx53/imx6 Wjatscheslaw Stoljarski
@ 2015-01-29 9:21 ` Sascha Hauer
2015-01-29 19:25 ` Robert Jarzmik
0 siblings, 1 reply; 7+ messages in thread
From: Sascha Hauer @ 2015-01-29 9:21 UTC (permalink / raw)
To: Wjatscheslaw Stoljarski; +Cc: barebox
On Thu, Jan 29, 2015 at 10:12:46AM +0100, Wjatscheslaw Stoljarski wrote:
> Hello,
>
> If I try to read from first 4k RAM on imx53/imx6, with md or from code,
> barebox show stacktrace with mesage:
> "unable to handle NULL pointer dereference at address 0x...".
> Is it possible in some way do that?
The only way I know is to disable CONFIG_MMU in the config.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-29 9:21 ` Sascha Hauer
@ 2015-01-29 19:25 ` Robert Jarzmik
2015-01-30 7:40 ` Sascha Hauer
0 siblings, 1 reply; 7+ messages in thread
From: Robert Jarzmik @ 2015-01-29 19:25 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
Sascha Hauer <s.hauer@pengutronix.de> writes:
> On Thu, Jan 29, 2015 at 10:12:46AM +0100, Wjatscheslaw Stoljarski wrote:
>> Hello,
>>
>> If I try to read from first 4k RAM on imx53/imx6, with md or from code,
>> barebox show stacktrace with mesage:
>> "unable to handle NULL pointer dereference at address 0x...".
>> Is it possible in some way do that?
>
> The only way I know is to disable CONFIG_MMU in the config.
I think the solution in arch/arm/boards/mioa701/board.c (remapping the 0x0
address) should work here :
docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);
Cheers.
--
Robert
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-29 19:25 ` Robert Jarzmik
@ 2015-01-30 7:40 ` Sascha Hauer
2015-01-30 9:58 ` Jan Lübbe
2015-01-30 18:51 ` Robert Jarzmik
0 siblings, 2 replies; 7+ messages in thread
From: Sascha Hauer @ 2015-01-30 7:40 UTC (permalink / raw)
To: Robert Jarzmik; +Cc: barebox
On Thu, Jan 29, 2015 at 08:25:54PM +0100, Robert Jarzmik wrote:
> Sascha Hauer <s.hauer@pengutronix.de> writes:
>
> > On Thu, Jan 29, 2015 at 10:12:46AM +0100, Wjatscheslaw Stoljarski wrote:
> >> Hello,
> >>
> >> If I try to read from first 4k RAM on imx53/imx6, with md or from code,
> >> barebox show stacktrace with mesage:
> >> "unable to handle NULL pointer dereference at address 0x...".
> >> Is it possible in some way do that?
> >
> > The only way I know is to disable CONFIG_MMU in the config.
> I think the solution in arch/arm/boards/mioa701/board.c (remapping the 0x0
> address) should work here :
> docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);
We could create a /dev/zeropage with the code above. That would make the
zero page generally available. I don't know if this is worth the effort
though.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-30 7:40 ` Sascha Hauer
@ 2015-01-30 9:58 ` Jan Lübbe
2015-01-30 18:51 ` Robert Jarzmik
1 sibling, 0 replies; 7+ messages in thread
From: Jan Lübbe @ 2015-01-30 9:58 UTC (permalink / raw)
To: barebox
On Fr, 2015-01-30 at 08:40 +0100, Sascha Hauer wrote:
> On Thu, Jan 29, 2015 at 08:25:54PM +0100, Robert Jarzmik wrote:
> > Sascha Hauer <s.hauer@pengutronix.de> writes:
> >
> > > On Thu, Jan 29, 2015 at 10:12:46AM +0100, Wjatscheslaw Stoljarski
> wrote:
> > >> Hello,
> > >>
> > >> If I try to read from first 4k RAM on imx53/imx6, with md or from
> code,
> > >> barebox show stacktrace with mesage:
> > >> "unable to handle NULL pointer dereference at address 0x...".
> > >> Is it possible in some way do that?
> > >
> > > The only way I know is to disable CONFIG_MMU in the config.
> > I think the solution in arch/arm/boards/mioa701/board.c (remapping
> the 0x0
> > address) should work here :
> > docg3_iospace = map_io_sections(0x0, (void *)0xe0000000,
> 0x2000);
>
> We could create a /dev/zeropage with the code above. That would make
> the zero page generally available. I don't know if this is worth the
> effort though.
Couldn't we special-case the zero page in /dev/mem instead?
Regards,
Jan
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-30 7:40 ` Sascha Hauer
2015-01-30 9:58 ` Jan Lübbe
@ 2015-01-30 18:51 ` Robert Jarzmik
2015-02-02 9:14 ` Sascha Hauer
1 sibling, 1 reply; 7+ messages in thread
From: Robert Jarzmik @ 2015-01-30 18:51 UTC (permalink / raw)
To: Sascha Hauer; +Cc: barebox
Sascha Hauer <s.hauer@pengutronix.de> writes:
> On Thu, Jan 29, 2015 at 08:25:54PM +0100, Robert Jarzmik wrote:
>> Sascha Hauer <s.hauer@pengutronix.de> writes:
>> I think the solution in arch/arm/boards/mioa701/board.c (remapping the 0x0
>> address) should work here :
>> docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);
>
> We could create a /dev/zeropage with the code above. That would make the
> zero page generally available. I don't know if this is worth the effort
> though.
Yeah, I don't know if it's worth it either. And how "big" should this
/dev/zeropage be (4k, 1M, ...) ?
Cheers.
--
Robert
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Access to first 0x1000 byte on imx53/imx6
2015-01-30 18:51 ` Robert Jarzmik
@ 2015-02-02 9:14 ` Sascha Hauer
0 siblings, 0 replies; 7+ messages in thread
From: Sascha Hauer @ 2015-02-02 9:14 UTC (permalink / raw)
To: Robert Jarzmik; +Cc: barebox
On Fri, Jan 30, 2015 at 07:51:19PM +0100, Robert Jarzmik wrote:
> Sascha Hauer <s.hauer@pengutronix.de> writes:
>
> > On Thu, Jan 29, 2015 at 08:25:54PM +0100, Robert Jarzmik wrote:
> >> Sascha Hauer <s.hauer@pengutronix.de> writes:
> >> I think the solution in arch/arm/boards/mioa701/board.c (remapping the 0x0
> >> address) should work here :
> >> docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);
> >
> > We could create a /dev/zeropage with the code above. That would make the
> > zero page generally available. I don't know if this is worth the effort
> > though.
>
> Yeah, I don't know if it's worth it either. And how "big" should this
> /dev/zeropage be (4k, 1M, ...) ?
It should be one page, so 4k. But as Jan said, special casing the first
page in /dev/mem sounds better.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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^ permalink raw reply [flat|nested] 7+ messages in thread
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2015-01-29 9:12 Access to first 0x1000 byte on imx53/imx6 Wjatscheslaw Stoljarski
2015-01-29 9:21 ` Sascha Hauer
2015-01-29 19:25 ` Robert Jarzmik
2015-01-30 7:40 ` Sascha Hauer
2015-01-30 9:58 ` Jan Lübbe
2015-01-30 18:51 ` Robert Jarzmik
2015-02-02 9:14 ` Sascha Hauer
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