[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Fabrizio Castro]

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.

 arch/arm/configs/shmobile_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/shmobile_defconfig b/arch/arm/configs/shmobile_defconfig
index dd95d39..21b25e9 100644
--- a/arch/arm/configs/shmobile_defconfig
+++ b/arch/arm/configs/shmobile_defconfig
@@ -23,6 +23,7 @@ CONFIG_ARCH_R8A7792=y
 CONFIG_ARCH_R8A7793=y
 CONFIG_ARCH_R8A7794=y
 CONFIG_ARCH_SH73A0=y
+CONFIG_ARM_LPAE=y
 CONFIG_PL310_ERRATA_588369=y
 CONFIG_ARM_ERRATA_754322=y
 CONFIG_PCI=y
-- 
2.7.4

[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Fabrizio Castro]

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.

 arch/arm/configs/shmobile_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/shmobile_defconfig b/arch/arm/configs/shmobile_defconfig
index dd95d39..21b25e9 100644
--- a/arch/arm/configs/shmobile_defconfig
+++ b/arch/arm/configs/shmobile_defconfig
@@ -23,6 +23,7 @@ CONFIG_ARCH_R8A7792=y
 CONFIG_ARCH_R8A7793=y
 CONFIG_ARCH_R8A7794=y
 CONFIG_ARCH_SH73A0=y
+CONFIG_ARM_LPAE=y
 CONFIG_PL310_ERRATA_588369=y
 CONFIG_ARM_ERRATA_754322=y
 CONFIG_PCI=y
-- 
2.7.4

Re: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Florian Fainelli]

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

[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Florian Fainelli]

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

Re: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Geert Uytterhoeven]

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

[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Geert Uytterhoeven]

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

RE: [PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Fabrizio Castro]

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.

[PATCH/RFC v2] ARM: shmobile: defconfig: Enable LPAE

[Fabrizio Castro]

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.