RE: [RFC PATCH v4 28/28] board: keymile: common: Use environment to store IVM_* variables.

Holger Brunck
2022-06-20T16:08:40Z

> > > On Fri, Jun 17, 2022 at 12:31:58AM +0200, Francis Laniel wrote:
> > >
> > > > These boards used set_local_var() to store some variables as local shell.
> > > > They then used get_local_var() to retrieve the variables values.
> > > >
> > > > Instead of using local shell variables, they should use
> > > > environment ones (like a majority of board).
> > > > So, this patch converts using local variables to environment ones.
> > > >
> >
> > why do we need to change that? It is intended that we use this hush
> > variable infrastructure from u-boot (common/hush.c) for our IVM data
> > and not the standard env. We read the IVM at boot time and store these
> > values in RAM. It is not intended to store them permanently in the
> > flash or wherever the environment is saved. Especially in our case we
> > have some boards where the environment is in a i2c EEPROM and we don't
> > want to write down to the EEPROM each time when the board is starting.
>
> So, the whole series is about updating hush to bring in a new baseline version of
> the shell, from busybox.
>

Ok.

> > > > Signed-off-by: Francis Laniel
> > > > <francis.laniel@amarulasolutions.com>
> > > > ---
> > > > board/keymile/common/common.c | 8 ++++----
> > > > board/keymile/common/ivm.c | 9 +--------
> > > > 2 files changed, 5 insertions(+), 12 deletions(-)
> > > >
> > > > diff --git a/board/keymile/common/common.c
> > > > b/board/keymile/common/common.c index 3999f48719..72939af36e
> > > > 100644
> > > > --- a/board/keymile/common/common.c
> > > > +++ b/board/keymile/common/common.c
> > > > @@ -219,7 +219,7 @@ static int do_setboardid(struct cmd_tbl
> > > > *cmdtp, int
> > > flag, int argc,
> > > > unsigned char buf[32];
> > > > char *p;
> > > >
> > > > - p = get_local_var("IVM_BoardId");
> > > > + p = env_get("IVM_BoardId");
> > > > if (!p) {
> > > > printf("can't get the IVM_Boardid\n");
> > > > return 1;
> > > > @@ -228,7 +228,7 @@ static int do_setboardid(struct cmd_tbl
> > > > *cmdtp, int
> > > flag, int argc,
> > > > env_set("boardid", (char *)buf);
> > > > printf("set boardid=%s\n", buf);
> > > >
> > > > - p = get_local_var("IVM_HWKey");
> > > > + p = env_get("IVM_HWKey");
> > > > if (!p) {
> > > > printf("can't get the IVM_HWKey\n");
> > > > return 1;
> > > > @@ -272,14 +272,14 @@ static int do_checkboardidhwk(struct cmd_tbl
> > > *cmdtp, int flag, int argc,
> > > > * first read out the real inventory values, these values are
> > > > * already stored in the local hush variables
> > > > */
> > > > - p = get_local_var("IVM_BoardId");
> > > > + p = env_get("IVM_BoardId");
> > > > if (!p) {
> > > > printf("can't get the IVM_Boardid\n");
> > > > return 1;
> > > > }
> > > > rc = strict_strtoul(p, 16, &ivmbid);
> > > >
> > > > - p = get_local_var("IVM_HWKey");
> > > > + p = env_get("IVM_HWKey");
> > > > if (!p) {
> > > > printf("can't get the IVM_HWKey\n");
> > > > return 1;
> > > > diff --git a/board/keymile/common/ivm.c
> > > > b/board/keymile/common/ivm.c index 67db0c50f4..e266d7ce81 100644
> > > > --- a/board/keymile/common/ivm.c
> > > > +++ b/board/keymile/common/ivm.c
> > > > @@ -44,14 +44,7 @@ static int ivm_calc_crc(unsigned char *buf, int
> > > > len)
> > > >
> > > > static int ivm_set_value(char *name, char *value) {
> > > > - char tempbuf[256];
> > > > -
> > > > - if (value) {
> > > > - sprintf(tempbuf, "%s=%s", name, value);
> > > > - return set_local_var(tempbuf, 0);
> > > > - }
> > > > - unset_local_var(name);
> > > > - return 0;
> > > > + return env_set(name, value);
> >
> > this means we are now writing always down to the permanent environment
> > or? And this I would really like to avoid in our case.
>
> Note that "env_set" does not force a save of the running environment.

Ah yes you are right. But still for the first boot of our board we will call saveenv
to store an initial environment and with this change it would also write down
the IVM data which is currently only stored temporary in RAM.

> These variables will be exposed to the CLI run-time, which I am not sure if they
> are today, so if the user then does "saveenv" they will be written. That I think
> would be a functional difference.
>

yes exactly and I wonder if this functionality will be also possible after the rework.
I mean our use case (even it seems we are the only ones using it) is quite useful
I think. We read out inventory data from an EEPROM and they are parsed and
temporary stored in RAM and then we are able to use them as any other
environment variables without the need to store them permanently. I also would
like to avoid this as the data should be permanently in the IVM only and not stored
a second time permanently in flash.

Best regards
Holger