* [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
@ 2018-04-25 18:17 ` Florian Fainelli
0 siblings, 0 replies; 8+ messages in thread
From: Florian Fainelli @ 2018-04-25 18:17 UTC (permalink / raw)
To: linux-arm-kernel
On 04/25/2018 09:14 AM, Fabrizio Castro wrote:
> On iWave's iwg20m DDR1 512MB memory cannot be accessed with 32-bit
> addresses, hence we need LPAE.
>
> Signed-off-by: Biju Das <biju.das@bp.renesas.com>
> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> ---
> This information is mentioned in the "RZ/G Series User?s Manual: Hardware",
> Chapter 2, Area Map. Is this patch going to break the functionality of other
> boards? Comments welcome.
LPAE is not supported by all Cortex-A class cores, for instance
Cortex-A9 does not support LPAE, if you have boards using such cores,
then this would result in a kernel that would not boot on these
platforms. Can that be a problem with the shmobile_defconfig?
--
Florian
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
2018-04-25 18:17 ` Florian Fainelli
@ 2018-04-25 18:29 ` Geert Uytterhoeven
-1 siblings, 0 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2018-04-25 18:29 UTC (permalink / raw)
To: Florian Fainelli
Cc: Fabrizio Castro, Simon Horman, Geert Uytterhoeven,
Chris Paterson, Magnus Damm, Russell King, Biju Das,
Linux-Renesas, Linux ARM
Hi Florian,
On Wed, Apr 25, 2018 at 8:17 PM, Florian Fainelli <f.fainelli@gmail.com> wrote:
> On 04/25/2018 09:14 AM, Fabrizio Castro wrote:
>> On iWave's iwg20m DDR1 512MB memory cannot be accessed with 32-bit
>> addresses, hence we need LPAE.
>>
>> Signed-off-by: Biju Das <biju.das@bp.renesas.com>
>> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
>> ---
>> This information is mentioned in the "RZ/G Series User’s Manual: Hardware",
>> Chapter 2, Area Map. Is this patch going to break the functionality of other
>> boards? Comments welcome.
>
> LPAE is not supported by all Cortex-A class cores, for instance
> Cortex-A9 does not support LPAE, if you have boards using such cores,
Thanks for reminding me!
> then this would result in a kernel that would not boot on these
> platforms. Can that be a problem with the shmobile_defconfig?
Yes it is...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
@ 2018-04-25 18:29 ` Geert Uytterhoeven
0 siblings, 0 replies; 8+ messages in thread
From: Geert Uytterhoeven @ 2018-04-25 18:29 UTC (permalink / raw)
To: linux-arm-kernel
Hi Florian,
On Wed, Apr 25, 2018 at 8:17 PM, Florian Fainelli <f.fainelli@gmail.com> wrote:
> On 04/25/2018 09:14 AM, Fabrizio Castro wrote:
>> On iWave's iwg20m DDR1 512MB memory cannot be accessed with 32-bit
>> addresses, hence we need LPAE.
>>
>> Signed-off-by: Biju Das <biju.das@bp.renesas.com>
>> Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
>> ---
>> This information is mentioned in the "RZ/G Series User?s Manual: Hardware",
>> Chapter 2, Area Map. Is this patch going to break the functionality of other
>> boards? Comments welcome.
>
> LPAE is not supported by all Cortex-A class cores, for instance
> Cortex-A9 does not support LPAE, if you have boards using such cores,
Thanks for reminding me!
> then this would result in a kernel that would not boot on these
> platforms. Can that be a problem with the shmobile_defconfig?
Yes it is...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 8+ messages in thread
* RE: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
2018-04-25 18:17 ` Florian Fainelli
@ 2018-04-26 9:34 ` Fabrizio Castro
-1 siblings, 0 replies; 8+ messages in thread
From: Fabrizio Castro @ 2018-04-26 9:34 UTC (permalink / raw)
To: Florian Fainelli, Simon Horman, Geert Uytterhoeven
Cc: Chris Paterson, Magnus Damm, Russell King, Biju Das,
linux-renesas-soc, linux-arm-kernel
Hello Florian,
Thank you for your feedback!
> Subject: Re: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
>
> On 04/25/2018 09:14 AM, Fabrizio Castro wrote:
> > On iWave's iwg20m DDR1 512MB memory cannot be accessed with 32-bit
> > addresses, hence we need LPAE.
> >
> > Signed-off-by: Biju Das <biju.das@bp.renesas.com>
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > ---
> > This information is mentioned in the "RZ/G Series User’s Manual: Hardware",
> > Chapter 2, Area Map. Is this patch going to break the functionality of other
> > boards? Comments welcome.
>
> LPAE is not supported by all Cortex-A class cores, for instance
> Cortex-A9 does not support LPAE, if you have boards using such cores,
> then this would result in a kernel that would not boot on these
> platforms. Can that be a problem with the shmobile_defconfig?
It definitely is, therefore I am going to drop this patch as it would break things.
Best regards,
Fab
> --
> Florian
Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
@ 2018-04-26 9:34 ` Fabrizio Castro
0 siblings, 0 replies; 8+ messages in thread
From: Fabrizio Castro @ 2018-04-26 9:34 UTC (permalink / raw)
To: linux-arm-kernel
Hello Florian,
Thank you for your feedback!
> Subject: Re: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE
>
> On 04/25/2018 09:14 AM, Fabrizio Castro wrote:
> > On iWave's iwg20m DDR1 512MB memory cannot be accessed with 32-bit
> > addresses, hence we need LPAE.
> >
> > Signed-off-by: Biju Das <biju.das@bp.renesas.com>
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > ---
> > This information is mentioned in the "RZ/G Series User?s Manual: Hardware",
> > Chapter 2, Area Map. Is this patch going to break the functionality of other
> > boards? Comments welcome.
>
> LPAE is not supported by all Cortex-A class cores, for instance
> Cortex-A9 does not support LPAE, if you have boards using such cores,
> then this would result in a kernel that would not boot on these
> platforms. Can that be a problem with the shmobile_defconfig?
It definitely is, therefore I am going to drop this patch as it would break things.
Best regards,
Fab
> --
> Florian
Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
^ permalink raw reply [flat|nested] 8+ messages in thread