Access to first 0x1000 byte on imx53/imx6
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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Quoted 6 lines · Wjatscheslaw Stoljarski
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
Signature · 9 lines
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 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
Quoted 9 lines · Sascha Hauer
Quoted 6 lines · Wjatscheslaw Stoljarski
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_MMUin 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.
Signature · 6 lines
Robert _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
Quoted 10 lines · Robert Jarzmik
Quoted 8 lines · Sascha Hauer
Quoted 6 lines · Wjatscheslaw Stoljarski
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?
Quoted 4 lines
Quoted 1 line
The only way I know is to disable
CONFIG_MMUin the config.I think the solution in
arch/arm/boards/mioa701/board.c(remapping the0x0address) 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
Signature · 9 lines
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 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
Quoted 15 lines · Sascha Hauer
Quoted 3 lines · Robert Jarzmik
Quoted 1 line · Sascha Hauer
On Thu, Jan 29, 2015 at 10:12:46AM +0100, Wjatscheslaw Stoljarski
Quoted 3 lines · wrote:
Quoted 3 lines
Quoted 3 lines
Hello,
If I try to read from first 4k RAM on imx53/imx6, with md or from
code,
Quoted 6 lines
Quoted 5 lines
Quoted 3 lines
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_MMUin the config.I think the solution in
arch/arm/boards/mioa701/board.c(remapping
Quoted 8 lines
the
0x0Quoted 2 lines
address) should work here :
docg3_iospace = map_io_sections(0x0, (void *)0xe0000000,
0x2000);We could create a
/dev/zeropagewith 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
Signature · 10 lines
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 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
Quoted 9 lines · Sascha Hauer
Quoted 4 lines · Robert Jarzmik
Sascha Hauer <[email protected]> writes:
I think the solution inarch/arm/boards/mioa701/board.c(remapping the0x0address) should work here :docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);We could create a
/dev/zeropagewith 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.
Signature · 6 lines
Robert _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
Quoted 8 lines · Robert Jarzmik
Quoted 6 lines · Sascha Hauer
Quoted 4 lines · Robert Jarzmik
Sascha Hauer <[email protected]> writes:
I think the solution inarch/arm/boards/mioa701/board.c(remapping the0x0address) should work here :docg3_iospace = map_io_sections(0x0, (void *)0xe0000000, 0x2000);
Quoted 6 lines
Quoted 3 lines
We could create a
/dev/zeropagewith 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/zeropagebe (4k, 1M, ...) ?
It should be one page, so 4k. But as Jan said, special casing the first page in /dev/mem sounds better.
Sascha
Signature · 9 lines
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 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox