[PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Timur Tabi]

Remove the "select PHYS_64BIT" from the Kconfig entry for the P1022DS,
so that large physical address support is a selectable option for non-CoreNet
reference boards.

The option is enabled in mpc85xx_[smp_]defconfig so that the default is
unchanged.  However, now it can be deselected.

The P1022DS had this option defined because the default device tree for
this board uses 36-bit addresses.  This had the side-effect of forcing
this option on for all boards that use mpc85xx_[smp_]defconfig.  Some
users may want to disable this feature to create an optimized configuration
for boards with <= 2GB of RAM.

Signed-off-by: Timur Tabi <timur@freescale.com>
---
 arch/powerpc/configs/mpc85xx_defconfig     |    1 +
 arch/powerpc/configs/mpc85xx_smp_defconfig |    1 +
 arch/powerpc/platforms/85xx/Kconfig        |    1 -
 3 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/configs/mpc85xx_defconfig b/arch/powerpc/configs/mpc85xx_defconfig
index f37a2ab..5fb0c8a 100644
--- a/arch/powerpc/configs/mpc85xx_defconfig
+++ b/arch/powerpc/configs/mpc85xx_defconfig
@@ -1,4 +1,5 @@
 CONFIG_PPC_85xx=y
+CONFIG_PHYS_64BIT=y
 CONFIG_EXPERIMENTAL=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
diff --git a/arch/powerpc/configs/mpc85xx_smp_defconfig b/arch/powerpc/configs/mpc85xx_smp_defconfig
index abdcd31..fb51bc9 100644
--- a/arch/powerpc/configs/mpc85xx_smp_defconfig
+++ b/arch/powerpc/configs/mpc85xx_smp_defconfig
@@ -1,4 +1,5 @@
 CONFIG_PPC_85xx=y
+CONFIG_PHYS_64BIT=y
 CONFIG_SMP=y
 CONFIG_NR_CPUS=8
 CONFIG_EXPERIMENTAL=y
diff --git a/arch/powerpc/platforms/85xx/Kconfig b/arch/powerpc/platforms/85xx/Kconfig
index d7946be..93d27e2 100644
--- a/arch/powerpc/platforms/85xx/Kconfig
+++ b/arch/powerpc/platforms/85xx/Kconfig
@@ -80,7 +80,6 @@ config P1010_RDB
 config P1022_DS
 	bool "Freescale P1022 DS"
 	select DEFAULT_UIMAGE
-	select PHYS_64BIT	# The DTS has 36-bit addresses
 	select SWIOTLB
 	help
 	  This option enables support for the Freescale P1022DS reference board.
-- 
1.7.3.4

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Huang Changming-R66093]

I have one similar patch to remove the "select PHYS_64BIT".
http://patchwork.ozlabs.org/patch/132351/


Thanks
Jerry Huang


> -----Original Message-----
> From: linuxppc-dev-bounces+r66093=3Dfreescale.com@lists.ozlabs.org
> [mailto:linuxppc-dev-bounces+r66093=3Dfreescale.com@lists.ozlabs.org] On
> Behalf Of Timur Tabi
> Sent: Wednesday, February 22, 2012 3:53 AM
> To: galak@kernel.crashing.org; benh@kernel.crashing.org; Wood Scott-
> B07421; Li Yang-R58472; linuxppc-dev@ozlabs.org
> Subject: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable
>=20
> Remove the "select PHYS_64BIT" from the Kconfig entry for the P1022DS, so
> that large physical address support is a selectable option for non-
> CoreNet reference boards.
>=20
> The option is enabled in mpc85xx_[smp_]defconfig so that the default is
> unchanged.  However, now it can be deselected.
>=20
> The P1022DS had this option defined because the default device tree for
> this board uses 36-bit addresses.  This had the side-effect of forcing
> this option on for all boards that use mpc85xx_[smp_]defconfig.  Some
> users may want to disable this feature to create an optimized
> configuration for boards with <=3D 2GB of RAM.
>=20
> Signed-off-by: Timur Tabi <timur@freescale.com>
> ---
>  arch/powerpc/configs/mpc85xx_defconfig     |    1 +
>  arch/powerpc/configs/mpc85xx_smp_defconfig |    1 +
>  arch/powerpc/platforms/85xx/Kconfig        |    1 -
>  3 files changed, 2 insertions(+), 1 deletions(-)
>=20
> diff --git a/arch/powerpc/configs/mpc85xx_defconfig
> b/arch/powerpc/configs/mpc85xx_defconfig
> index f37a2ab..5fb0c8a 100644
> --- a/arch/powerpc/configs/mpc85xx_defconfig
> +++ b/arch/powerpc/configs/mpc85xx_defconfig
> @@ -1,4 +1,5 @@
>  CONFIG_PPC_85xx=3Dy
> +CONFIG_PHYS_64BIT=3Dy
>  CONFIG_EXPERIMENTAL=3Dy
>  CONFIG_SYSVIPC=3Dy
>  CONFIG_POSIX_MQUEUE=3Dy
> diff --git a/arch/powerpc/configs/mpc85xx_smp_defconfig
> b/arch/powerpc/configs/mpc85xx_smp_defconfig
> index abdcd31..fb51bc9 100644
> --- a/arch/powerpc/configs/mpc85xx_smp_defconfig
> +++ b/arch/powerpc/configs/mpc85xx_smp_defconfig
> @@ -1,4 +1,5 @@
>  CONFIG_PPC_85xx=3Dy
> +CONFIG_PHYS_64BIT=3Dy
>  CONFIG_SMP=3Dy
>  CONFIG_NR_CPUS=3D8
>  CONFIG_EXPERIMENTAL=3Dy
> diff --git a/arch/powerpc/platforms/85xx/Kconfig
> b/arch/powerpc/platforms/85xx/Kconfig
> index d7946be..93d27e2 100644
> --- a/arch/powerpc/platforms/85xx/Kconfig
> +++ b/arch/powerpc/platforms/85xx/Kconfig
> @@ -80,7 +80,6 @@ config P1010_RDB
>  config P1022_DS
>  	bool "Freescale P1022 DS"
>  	select DEFAULT_UIMAGE
> -	select PHYS_64BIT	# The DTS has 36-bit addresses
>  	select SWIOTLB
>  	help
>  	  This option enables support for the Freescale P1022DS reference
> board.
> --
> 1.7.3.4
>=20
>=20
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Huang Changming-R66093 wrote:
> I have one similar patch to remove the "select PHYS_64BIT".
> http://patchwork.ozlabs.org/patch/132351/

That one doesn't update the defconfigs, which means that the default=20
kernel will not have PHYS_64BIT enabled.

--=20
Timur Tabi
Linux kernel developer at Freescale=

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Huang Changming-R66093]

> -----Original Message-----
> From: Tabi Timur-B04825
> Sent: Thursday, February 23, 2012 8:25 PM
> To: Huang Changming-R66093
> Cc: galak@kernel.crashing.org; benh@kernel.crashing.org; Wood Scott-
> B07421; Li Yang-R58472; linuxppc-dev@ozlabs.org
> Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> selectable
>=20
> Huang Changming-R66093 wrote:
> > I have one similar patch to remove the "select PHYS_64BIT".
> > http://patchwork.ozlabs.org/patch/132351/
>=20
> That one doesn't update the defconfigs, which means that the default
> kernel will not have PHYS_64BIT enabled.
I think it is not necessary to enable the 64BIT,
if customer want to enable it, he can do it manually.=20

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Li Yang-R58472]

> > Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> > selectable
> >
> > Huang Changming-R66093 wrote:
> > > I have one similar patch to remove the "select PHYS_64BIT".
> > > http://patchwork.ozlabs.org/patch/132351/
> >
> > That one doesn't update the defconfigs, which means that the default
> > kernel will not have PHYS_64BIT enabled.
> I think it is not necessary to enable the 64BIT, if customer want to
> enable it, he can do it manually.

I agree with Changming that we shouldn't setting PHYS_64BIT by default.  Fo=
r the platforms covered by the mpc85xx_defconfig, most user won't need the =
PHYS_64BIT.  We shouldn't set the one with worse performance and unnecessar=
y to most people as default.  Also all these platforms supports 32-bit mode=
.

- Leo

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Li Yang-R58472 wrote:

> I agree with Changming that we shouldn't setting PHYS_64BIT by default.

The default kernel should always be the compatible with as much as=20
possible.  Disabling PHYS_64BIT by default means that the default kernel=20
will not work with a 36-bit DTS.  If you attempt to boot such a kernel=20
with a 36-bit DTS, there will be no text output.  Most people will not=20
know why it's not working.

So the safest option is for PHYS_64BIT to be enabled by default.  That=20
way, the kernel will always work.

--=20
Timur Tabi
Linux kernel developer at Freescale=

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Li Yang-R58472]

> -----Original Message-----
> From: Tabi Timur-B04825
> Sent: Friday, February 24, 2012 10:46 AM
> To: Li Yang-R58472
> Cc: Huang Changming-R66093; galak@kernel.crashing.org;
> benh@kernel.crashing.org; Wood Scott-B07421; linuxppc-dev@ozlabs.org
> Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> selectable
>=20
> Li Yang-R58472 wrote:
>=20
> > I agree with Changming that we shouldn't setting PHYS_64BIT by default.
>=20
> The default kernel should always be the compatible with as much as
> possible.  Disabling PHYS_64BIT by default means that the default kernel
> will not work with a 36-bit DTS.  If you attempt to boot such a kernel
> with a 36-bit DTS, there will be no text output.  Most people will not
> know why it's not working.
>=20
> So the safest option is for PHYS_64BIT to be enabled by default.  That
> way, the kernel will always work.

Even though the user still need to know the addressing mode that u-boot is =
using.  It won't work if the addressing mode of u-boot and device tree are =
different.

- Leo

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Huang Changming-R66093]

> > -----Original Message-----
> > From: Tabi Timur-B04825
> > Sent: Friday, February 24, 2012 10:46 AM
> > To: Li Yang-R58472
> > Cc: Huang Changming-R66093; galak@kernel.crashing.org;
> > benh@kernel.crashing.org; Wood Scott-B07421; linuxppc-dev@ozlabs.org
> > Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> > selectable
> >
> > Li Yang-R58472 wrote:
> >
> > > I agree with Changming that we shouldn't setting PHYS_64BIT by
> default.
> >
> > The default kernel should always be the compatible with as much as
> > possible.  Disabling PHYS_64BIT by default means that the default
> > kernel will not work with a 36-bit DTS.  If you attempt to boot such a
> > kernel with a 36-bit DTS, there will be no text output.  Most people
> > will not know why it's not working.
> >
> > So the safest option is for PHYS_64BIT to be enabled by default.  That
> > way, the kernel will always work.
>=20
> Even though the user still need to know the addressing mode that u-boot
> is using.  It won't work if the addressing mode of u-boot and device tree
> are different.
>=20
Yes, u-boot must has the same address mode with DTS, otherwise, we can't bo=
ot the kernel.

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Li Yang-R58472 wrote:

> Even though the user still need to know the addressing mode that u-boot
> is using.  It won't work if the addressing mode of u-boot and device
> tree are different.

U-Boot will tell the user if the DT does not match.  I added code to=20
U-Boot to do that.  So if you have a 36-bit U-Boot and a 32-bit DT, then=20
you will get a warning.  If you have a 36-bit U-boot and a 36-bit DT and a=
=20
32-bit kernel, you will get nothing.  But if you have a 32-bit U-boot and=20
a 32-bit DT and a 36-bit kernel, then that will work.  A 36-bit kernel=20
works with 32-bit *and* 36-bit DTs.  This is why a 36-bit kernel should be=
=20
the default.

--=20
Timur Tabi
Linux kernel developer at Freescale=

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Huang Changming-R66093]

>=20
> Li Yang-R58472 wrote:
>=20
> > Even though the user still need to know the addressing mode that
> > u-boot is using.  It won't work if the addressing mode of u-boot and
> > device tree are different.
>=20
> U-Boot will tell the user if the DT does not match.  I added code to U-
> Boot to do that.  So if you have a 36-bit U-Boot and a 32-bit DT, then
> you will get a warning.  If you have a 36-bit U-boot and a 36-bit DT and
> a 32-bit kernel, you will get nothing.  But if you have a 32-bit U-boot
> and a 32-bit DT and a 36-bit kernel, then that will work.  A 36-bit
> kernel works with 32-bit *and* 36-bit DTs.  This is why a 36-bit kernel
> should be the default.
>=20
> --
Hi, Timur
I want to know if you have the other codes for different address?

The current U-boot just detect the base address of DTS and the CCSR address=
.
If they are different, u-boot will print the warning and return 0,
so the kernel can't been booted.


Jerry.

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Huang Changming-R66093 wrote:
> I want to know if you have the other codes for different address?
>
> The current U-boot just detect the base address of DTS and the CCSR addre=
ss.
> If they are different, u-boot will print the warning and return 0,
> so the kernel can't been booted.

I had a patch that verified some PCI addresses (which are sometimes=20
slightly mismatched), but Kumar rejected it.

I could add some more checks, but the 90% of the time, the only problem is=
=20
using the wrong size (32-bit vs 36-bit) DT.

--=20
Timur Tabi
Linux kernel developer at Freescale=

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Li Yang-R58472]

> Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> selectable
>=20
> Li Yang-R58472 wrote:
>=20
> > Even though the user still need to know the addressing mode that
> > u-boot is using.  It won't work if the addressing mode of u-boot and
> > device tree are different.
>=20
> U-Boot will tell the user if the DT does not match.  I added code to U-
> Boot to do that.  So if you have a 36-bit U-Boot and a 32-bit DT, then
> you will get a warning.  If you have a 36-bit U-boot and a 36-bit DT and
> a 32-bit kernel, you will get nothing.  But if you have a 32-bit U-boot
> and a 32-bit DT and a 36-bit kernel, then that will work.  A 36-bit
> kernel works with 32-bit *and* 36-bit DTs.  This is why a 36-bit kernel
> should be the default.

The mpc85xx_defconfig does include silicons with e500v1 core which doesn't =
have the 36-bit support.  Won't enabling 36-bit support by default break th=
e support for them?

- Leo

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Li Yang-R58472 wrote:

> The mpc85xx_defconfig does include silicons with e500v1 core which
> doesn't have the 36-bit support.  Won't enabling 36-bit support by
> default break the support for them?

No.  The kernel will detect at runtime that that it's an e500v1 core and=20
it won't try to create 36-bit TLBs. (e.g. it won't write to MAS7).

Please remember that the Kconfig for the P1022DS already forced PHYS_64BIT=
=20
for all mpc85xx platforms.  All we're doing is making it possible to=20
deselect PHYS_64BIT.

--=20
Timur Tabi
Linux kernel developer at Freescale=

RE: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Li Yang-R58472]

> Subject: Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be
> selectable
>=20
> Li Yang-R58472 wrote:
>=20
> > The mpc85xx_defconfig does include silicons with e500v1 core which
> > doesn't have the 36-bit support.  Won't enabling 36-bit support by
> > default break the support for them?
>=20
> No.  The kernel will detect at runtime that that it's an e500v1 core and
> it won't try to create 36-bit TLBs. (e.g. it won't write to MAS7).

It's a good point.  Why can't we decide to use 32-bit/36-bit TLB at runtime=
 even for e500v2?

>=20
> Please remember that the Kconfig for the P1022DS already forced
> PHYS_64BIT for all mpc85xx platforms.  All we're doing is making it
> possible to deselect PHYS_64BIT.

I think it's a side-effect introduced by P1022DS support and need to be fix=
ed.  There was no mentioning of enforcing 36-bit for all mpc85xx platforms.

- Leo

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Tabi Timur-B04825]

Li Yang-R58472 wrote:

> It's a good point.  Why can't we decide to use 32-bit/36-bit TLB at runti=
me even for e500v2?

That's not what PHYS_64BIT does.  PHYS_64BIT determines whether=20
phys_addr_t is a u64 or a u32.  This is something that must be determined=20
at compilation time.

>> Please remember that the Kconfig for the P1022DS already forced
>> PHYS_64BIT for all mpc85xx platforms.  All we're doing is making it
>> possible to deselect PHYS_64BIT.
>
> I think it's a side-effect introduced by P1022DS support and need to be f=
ixed.

Exactly.  That's what these patches do.  And these patches have been=20
applied to the SDK.  I'm just waiting for Kumar to apply them to his=20
repository.

> There was no mentioning of enforcing 36-bit for all mpc85xx platforms.

It's not enforcing, it's just the default.  If you build with=20
mpc85xx_smp_defconfig, then you'll get a 36-bit kernel.  But now you can=20
also use menuconfig to turn off PHYS_64BIT.  Before these fixes, that was=20
not possible.

--=20
Timur Tabi
Linux kernel developer at Freescale=

Re: [PATCH] powerpc/85xx: allow CONFIG_PHYS_64BIT to be selectable

[Kumar Gala]

On Feb 21, 2012, at 1:53 PM, Timur Tabi wrote:

> Remove the "select PHYS_64BIT" from the Kconfig entry for the P1022DS,
> so that large physical address support is a selectable option for =
non-CoreNet
> reference boards.
>=20
> The option is enabled in mpc85xx_[smp_]defconfig so that the default =
is
> unchanged.  However, now it can be deselected.
>=20
> The P1022DS had this option defined because the default device tree =
for
> this board uses 36-bit addresses.  This had the side-effect of forcing
> this option on for all boards that use mpc85xx_[smp_]defconfig.  Some
> users may want to disable this feature to create an optimized =
configuration
> for boards with <=3D 2GB of RAM.
>=20
> Signed-off-by: Timur Tabi <timur@freescale.com>
> ---
> arch/powerpc/configs/mpc85xx_defconfig     |    1 +
> arch/powerpc/configs/mpc85xx_smp_defconfig |    1 +
> arch/powerpc/platforms/85xx/Kconfig        |    1 -
> 3 files changed, 2 insertions(+), 1 deletions(-)

applied

- k=