From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Tue, 2 Jun 2020 17:55:25 +0200 Subject: [PATCH] env: Add option to only ever append environment In-Reply-To: <20200602143848.GH21630@bill-the-cat> References: <20200529175404.627741-1-marex@denx.de> <7f9cd3ee-6661-4780-90cf-d2e81591a7ce@prevas.dk> <02e0326f-c93c-da9e-e0ec-dd3bc2dc9e4a@prevas.dk> <20200602124450.GA21630@bill-the-cat> <20200602143848.GH21630@bill-the-cat> Message-ID: <098da29c-9457-9a8e-7ca2-67b71d3df8f9@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 6/2/20 4:38 PM, Tom Rini wrote: > On Tue, Jun 02, 2020 at 02:47:12PM +0200, Marek Vasut wrote: >> On 6/2/20 2:44 PM, Tom Rini wrote: >>> On Tue, Jun 02, 2020 at 02:05:39PM +0200, Rasmus Villemoes wrote: >>>> On 02/06/2020 13.04, Marek Vasut wrote: >>>>> On 6/2/20 8:42 AM, Rasmus Villemoes wrote: >>>>>> On 29/05/2020 19.54, Marek Vasut wrote: >>>>>>> +config ENV_APPEND >>>>>>> + bool "Always append the environment with new data" >>>>>>> + default n >>>>>>> + help >>>>>>> + If defined, the environment hash table is only ever appended with new >>>>>>> + data, but the existing hash table can never be dropped and reloaded >>>>>>> + with newly imported data. This may be used in combination with static >>>>>>> + flags to e.g. to protect variables which must not be modified. >>>>>>> + >>>>>>> config ENV_ACCESS_IGNORE_FORCE >>>>>>> bool "Block forced environment operations" >>>>>>> default n >>>>>>> diff --git a/env/env.c b/env/env.c >>>>>>> index 024d36fdbe..967a9d36d7 100644 >>>>>>> --- a/env/env.c >>>>>>> +++ b/env/env.c >>>>>>> @@ -204,7 +204,9 @@ int env_load(void) >>>>>>> ret = drv->load(); >>>>>>> if (!ret) { >>>>>>> printf("OK\n"); >>>>>>> +#if !CONFIG_IS_ENABLED(ENV_APPEND) >>>>>>> return 0; >>>>>>> +#endif >>>>>> >>>>>> Don't use CONFIG_IS_ENABLED() unless you actually introduce both >>>>>> CONFIG_FOO and CONFIG_SPL_FOO. Otherwise the above >>>>>> CONFIG_IS_ENABLED(ENV_APPEND) is guaranteed to evaluate to false in SPL. >>>>>> Of course that only matters if environment support is enabled in SPL, >>>>>> but some actually use that. >>>>> >>>>> We actually want to use CONFIG_IS_ENABLED() as much as possible to make >>>>> these options future-proof, so that others won't have to chase down all >>>>> kinds of #ifdef CONFIG stuff and fix it later on for SPL/TPL/etc. >>>>> >>>> >>>> That makes no sense. You're introducing something whose help text >>>> doesn't spell out that the option only applies to U-Boot proper, and is >>>> completely ignored in SPL (since CONFIG_SPL_ENV_APPEND never exists). >>>> The reason it's ignored in SPL is that you use the SPL-or-not-SPL-aware >>>> CONFIG_IS_ENABLED() helper, and you say that's so that somebody in the >>>> future can implement CONFIG_SPL_ENV_APPEND? >>>> >>>> If you intend for ENV_APPEND to be something that's either set or not >>>> set for a given board, then the code needs to use the SPL-agnostic >>>> IS_ENABLED(CONFIG_ENV_APPEND). If you intend it to be something that can >>>> be set independently for the env support in SPL vs U-Boot proper, you >>>> need to add both config options and, as you do, use CONFIG_IS_ENABLED. >>> >>> How will this code behave if there is a mismatch between SPL and full >>> U-Boot (disabled SPL, enabled full, as the patch stands today) ? >> >> One will append the environment, the other will override it (if you have >> multiple envs enabled). > > So it sounds like it wouldn't be valid to have this option differ > between SPL and main U-Boot? Consider the case where you have default env in SPL, and multiple envs in U-Boot proper.