[PATCH 3/3] env: mmc: fix offsets relative to the end of the partition

[PATCH 3/3] env: mmc: fix offsets relative to the end of the partition

[Michael Walle]

According to the help text, you can set negative offsets to indicated
that the offset is relative to the end of the parition. But kconfig
doesn't let you specify negative hex values. I think this fell through
the cracks when converting the symbol from a '#define' to a kconfig
option.

Introduce a new boolean kconfig option to switch on the "relative to the
end" behavior.

Signed-off-by: Michael Walle <mwalle@kernel.org>
---
 env/Kconfig | 42 +++++++++++++++++++++++++-----------------
 env/mmc.c   |  8 ++++++++
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/env/Kconfig b/env/Kconfig
index 4438f0b392c..49888bf700c 100644
--- a/env/Kconfig
+++ b/env/Kconfig
@@ -231,14 +231,6 @@ config ENV_IS_IN_MMC
 	  These two #defines specify the offset and size of the environment
 	  area within the specified MMC device.
 
-	  If offset is positive (the usual case), it is treated as relative to
-	  the start of the MMC partition. If offset is negative, it is treated
-	  as relative to the end of the MMC partition. This can be useful if
-	  your board may be fitted with different MMC devices, which have
-	  different sizes for the MMC partitions, and you always want the
-	  environment placed at the very end of the partition, to leave the
-	  maximum possible space before it, to store other data.
-
 	  These two values are in units of bytes, but must be aligned to an
 	  MMC sector boundary.
 
@@ -249,9 +241,6 @@ config ENV_IS_IN_MMC
 	  valid backup copy in case the other copy is corrupted, e.g. due
 	  to a power failure during a "saveenv" operation.
 
-	  This value may also be positive or negative; this is handled in the
-	  same way as CONFIG_ENV_OFFSET.
-
 	  In case CONFIG_SYS_MMC_ENV_PART is 1 (i.e. environment in eMMC boot
 	  partition) then setting CONFIG_ENV_OFFSET_REDUND to the same value
 	  as CONFIG_ENV_OFFSET makes use of the second eMMC boot partition for
@@ -592,9 +581,18 @@ config ENV_OFFSET
 	  Offset from the start of the device (or partition).
 
 	  This offset may be interpreted differently depending on the chosen
-	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
-	  be negative to indicate an offset backwards from the end of the
-	  partition. See the relevant help messages for more details.
+	  ENV_IS_IN_* options. See the relevant help messages for more details.
+
+config ENV_OFFSET_RELATIVE_END
+	bool "Offset is relative to the end of the partition"
+	depends on ENV_IS_IN_MMC
+	help
+	  Treat the environment offset as relative to the end of the MMC
+	  partition. This can be useful if your board may be fitted with
+	  different MMC devices, which have different sizes for the MMC
+	  partitions, and you always want the environment placed at the very end
+	  of the partition, to leave the maximum possible space before it, to
+	  store other data.
 
 config ENV_OFFSET_REDUND
 	hex "Redundant environment offset"
@@ -607,9 +605,19 @@ config ENV_OFFSET_REDUND
 	  environment location.
 
 	  This offset may be interpreted differently depending on the chosen
-	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
-	  be negative to indicate an offset backwards from the end of the
-	  partition. See the relevant help messages for more details.
+	  ENV_IS_IN_* options. See the relevant help messages for more details.
+
+config ENV_OFFSET_REDUND_RELATIVE_END
+	bool "Offset is relative to the end of the partition"
+	depends on SYS_REDUNDAND_ENVIRONMENT
+	depends on ENV_IS_IN_MMC
+	help
+	  Treat the redundnat environment offset as relative to the end of the
+	  MMC partition. This can be useful if your board may be fitted with
+	  different MMC devices, which have different sizes for the MMC
+	  partitions, and you always want the environment placed at the very end
+	  of the partition, to leave the maximum possible space before it, to
+	  store other data.
 
 config ENV_SIZE
 	hex "Environment Size"
diff --git a/env/mmc.c b/env/mmc.c
index 379f5ec9be7..fd8095f9793 100644
--- a/env/mmc.c
+++ b/env/mmc.c
@@ -29,11 +29,19 @@
 
 #else
 /* Default ENV offset when not defined in Device Tree */
+#if !defined(CONFIG_ENV_OFFSET_RELATIVE_END)
 #define ENV_MMC_OFFSET		CONFIG_ENV_OFFSET
+#else
+#define ENV_MMC_OFFSET		(-(CONFIG_ENV_OFFSET))
+#endif
 
 #if defined(CONFIG_ENV_OFFSET_REDUND)
+#if !defined(CONFIG_ENV_OFFSET_REDUND_RELATIVE_END)
 #define ENV_MMC_OFFSET_REDUND	CONFIG_ENV_OFFSET_REDUND
 #else
+#define ENV_MMC_OFFSET_REDUND	(-(CONFIG_ENV_OFFSET_REDUND))
+#endif
+#else
 #define ENV_MMC_OFFSET_REDUND	ENV_MMC_INVALID_OFFSET
 #endif
 #endif
-- 
2.39.5

Re: [PATCH 3/3] env: mmc: fix offsets relative to the end of the partition

[Michael Walle]

Sorry this should have been individual patches. Please read the subject 
as
"[PATCH 1/1]" or just "[PATCH]".

-michael

Re: [PATCH 3/3] env: mmc: fix offsets relative to the end of the partition

[Quentin Schulz]

Hi Michael,

On 3/12/25 8:40 AM, Michael Walle wrote:
> According to the help text, you can set negative offsets to indicated
> that the offset is relative to the end of the parition. But kconfig
> doesn't let you specify negative hex values. I think this fell through
> the cracks when converting the symbol from a '#define' to a kconfig
> option.
> 
> Introduce a new boolean kconfig option to switch on the "relative to the
> end" behavior.
> 
> Signed-off-by: Michael Walle <mwalle@kernel.org>
> ---
>   env/Kconfig | 42 +++++++++++++++++++++++++-----------------
>   env/mmc.c   |  8 ++++++++
>   2 files changed, 33 insertions(+), 17 deletions(-)
> 
> diff --git a/env/Kconfig b/env/Kconfig
> index 4438f0b392c..49888bf700c 100644
> --- a/env/Kconfig
> +++ b/env/Kconfig
> @@ -231,14 +231,6 @@ config ENV_IS_IN_MMC
>   	  These two #defines specify the offset and size of the environment
>   	  area within the specified MMC device.
>   
> -	  If offset is positive (the usual case), it is treated as relative to
> -	  the start of the MMC partition. If offset is negative, it is treated
> -	  as relative to the end of the MMC partition. This can be useful if
> -	  your board may be fitted with different MMC devices, which have
> -	  different sizes for the MMC partitions, and you always want the
> -	  environment placed at the very end of the partition, to leave the
> -	  maximum possible space before it, to store other data.
> -
>   	  These two values are in units of bytes, but must be aligned to an
>   	  MMC sector boundary.
>   
> @@ -249,9 +241,6 @@ config ENV_IS_IN_MMC
>   	  valid backup copy in case the other copy is corrupted, e.g. due
>   	  to a power failure during a "saveenv" operation.
>   
> -	  This value may also be positive or negative; this is handled in the
> -	  same way as CONFIG_ENV_OFFSET.
> -
>   	  In case CONFIG_SYS_MMC_ENV_PART is 1 (i.e. environment in eMMC boot
>   	  partition) then setting CONFIG_ENV_OFFSET_REDUND to the same value
>   	  as CONFIG_ENV_OFFSET makes use of the second eMMC boot partition for
> @@ -592,9 +581,18 @@ config ENV_OFFSET
>   	  Offset from the start of the device (or partition).
>   
>   	  This offset may be interpreted differently depending on the chosen
> -	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
> -	  be negative to indicate an offset backwards from the end of the
> -	  partition. See the relevant help messages for more details.
> +	  ENV_IS_IN_* options. See the relevant help messages for more details.
> +
> +config ENV_OFFSET_RELATIVE_END
> +	bool "Offset is relative to the end of the partition"
> +	depends on ENV_IS_IN_MMC
> +	help
> +	  Treat the environment offset as relative to the end of the MMC
> +	  partition. This can be useful if your board may be fitted with

I guess by MMC partition you meant hardware MMC partitions, as opposed 
to GPT/MBR partitions?

It's not clear from JEDEC standard if there's a word that would apply to 
the boot partitions, User Area (I think it can be split also?), RPMB, 
etc.? But if there's one, maybe use that term?

> +	  different MMC devices, which have different sizes for the MMC
> +	  partitions, and you always want the environment placed at the very end
> +	  of the partition, to leave the maximum possible space before it, to
> +	  store other data.
>   
>   config ENV_OFFSET_REDUND
>   	hex "Redundant environment offset"
> @@ -607,9 +605,19 @@ config ENV_OFFSET_REDUND
>   	  environment location.
>   
>   	  This offset may be interpreted differently depending on the chosen
> -	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
> -	  be negative to indicate an offset backwards from the end of the
> -	  partition. See the relevant help messages for more details.
> +	  ENV_IS_IN_* options. See the relevant help messages for more details.
> +
> +config ENV_OFFSET_REDUND_RELATIVE_END
> +	bool "Offset is relative to the end of the partition"
> +	depends on SYS_REDUNDAND_ENVIRONMENT
> +	depends on ENV_IS_IN_MMC
> +	help
> +	  Treat the redundnat environment offset as relative to the end of the

s/redundnat/redundant/

> +	  MMC partition. This can be useful if your board may be fitted with
> +	  different MMC devices, which have different sizes for the MMC
> +	  partitions, and you always want the environment placed at the very end
> +	  of the partition, to leave the maximum possible space before it, to
> +	  store other data.
>   

Same remark as for ENV_OFFSET_RELATIVE_END.

Looks good to me otherwise!

Cheers,
Quentin

Re: [PATCH 3/3] env: mmc: fix offsets relative to the end of the partition

[Michael Walle]

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Hi,

> > According to the help text, you can set negative offsets to indicated
> > that the offset is relative to the end of the parition. But kconfig
> > doesn't let you specify negative hex values. I think this fell through
> > the cracks when converting the symbol from a '#define' to a kconfig
> > option.
> > 
> > Introduce a new boolean kconfig option to switch on the "relative to the
> > end" behavior.
> > 
> > Signed-off-by: Michael Walle <mwalle@kernel.org>
> > ---
> >   env/Kconfig | 42 +++++++++++++++++++++++++-----------------
> >   env/mmc.c   |  8 ++++++++
> >   2 files changed, 33 insertions(+), 17 deletions(-)
> > 
> > diff --git a/env/Kconfig b/env/Kconfig
> > index 4438f0b392c..49888bf700c 100644
> > --- a/env/Kconfig
> > +++ b/env/Kconfig
> > @@ -231,14 +231,6 @@ config ENV_IS_IN_MMC
> >   	  These two #defines specify the offset and size of the environment
> >   	  area within the specified MMC device.
> >   
> > -	  If offset is positive (the usual case), it is treated as relative to
> > -	  the start of the MMC partition. If offset is negative, it is treated
> > -	  as relative to the end of the MMC partition. This can be useful if
> > -	  your board may be fitted with different MMC devices, which have
> > -	  different sizes for the MMC partitions, and you always want the
> > -	  environment placed at the very end of the partition, to leave the
> > -	  maximum possible space before it, to store other data.
> > -
> >   	  These two values are in units of bytes, but must be aligned to an
> >   	  MMC sector boundary.
> >   
> > @@ -249,9 +241,6 @@ config ENV_IS_IN_MMC
> >   	  valid backup copy in case the other copy is corrupted, e.g. due
> >   	  to a power failure during a "saveenv" operation.
> >   
> > -	  This value may also be positive or negative; this is handled in the
> > -	  same way as CONFIG_ENV_OFFSET.
> > -
> >   	  In case CONFIG_SYS_MMC_ENV_PART is 1 (i.e. environment in eMMC boot
> >   	  partition) then setting CONFIG_ENV_OFFSET_REDUND to the same value
> >   	  as CONFIG_ENV_OFFSET makes use of the second eMMC boot partition for
> > @@ -592,9 +581,18 @@ config ENV_OFFSET
> >   	  Offset from the start of the device (or partition).
> >   
> >   	  This offset may be interpreted differently depending on the chosen
> > -	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
> > -	  be negative to indicate an offset backwards from the end of the
> > -	  partition. See the relevant help messages for more details.
> > +	  ENV_IS_IN_* options. See the relevant help messages for more details.
> > +
> > +config ENV_OFFSET_RELATIVE_END
> > +	bool "Offset is relative to the end of the partition"
> > +	depends on ENV_IS_IN_MMC
> > +	help
> > +	  Treat the environment offset as relative to the end of the MMC
> > +	  partition. This can be useful if your board may be fitted with
>
> I guess by MMC partition you meant hardware MMC partitions, as opposed 
> to GPT/MBR partitions?

Yes exactly.

> It's not clear from JEDEC standard if there's a word that would apply to 
> the boot partitions, User Area (I think it can be split also?), RPMB, 
> etc.? But if there's one, maybe use that term?

I didn't come up with that, as I just moved the help text. But I can
certainly add "(hardware) MMC partition".

>
> > +	  different MMC devices, which have different sizes for the MMC
> > +	  partitions, and you always want the environment placed at the very end
> > +	  of the partition, to leave the maximum possible space before it, to
> > +	  store other data.
> >   
> >   config ENV_OFFSET_REDUND
> >   	hex "Redundant environment offset"
> > @@ -607,9 +605,19 @@ config ENV_OFFSET_REDUND
> >   	  environment location.
> >   
> >   	  This offset may be interpreted differently depending on the chosen
> > -	  ENV_IS_IN_* options. For example, for ENV_IS_IN_MMC=y, this offset may
> > -	  be negative to indicate an offset backwards from the end of the
> > -	  partition. See the relevant help messages for more details.
> > +	  ENV_IS_IN_* options. See the relevant help messages for more details.
> > +
> > +config ENV_OFFSET_REDUND_RELATIVE_END
> > +	bool "Offset is relative to the end of the partition"
> > +	depends on SYS_REDUNDAND_ENVIRONMENT
> > +	depends on ENV_IS_IN_MMC
> > +	help
> > +	  Treat the redundnat environment offset as relative to the end of the
>
> s/redundnat/redundant/
>
> > +	  MMC partition. This can be useful if your board may be fitted with
> > +	  different MMC devices, which have different sizes for the MMC
> > +	  partitions, and you always want the environment placed at the very end
> > +	  of the partition, to leave the maximum possible space before it, to
> > +	  store other data.
> >   
>
> Same remark as for ENV_OFFSET_RELATIVE_END.
>
> Looks good to me otherwise!

Thanks for reviewing.

Let's give this patch a couple more day, then I'll resend it with
your remarks being addressed.

-michael

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