On 12/04/18 10:33, Daniel Kiper wrote: > On Tue, Apr 10, 2018 at 11:09:33PM +0200, Daniel Kiper wrote: >> On Fri, Apr 06, 2018 at 03:08:23PM +0200, Kristian Amlie wrote: >>> On 06/04/18 14:35, Daniel Kiper wrote: >>>> On Fri, Apr 06, 2018 at 11:25:22AM +0200, Kristian Amlie wrote: >>>>> Hey, I work for Northern.tech, developing update software for embedded >>>>> Linux devices. >>>>> >>>>> I have a question about GRUB's environment block: This block is not >>>> >>>> I am not sure what exactly you mean by "GRUB's environment block". >>>> Could you send me some references to the code? >>> >>> Of course, sorry if the context wasn't clear. I'm talking about the >>> environment block mentioned here: >>> https://www.gnu.org/software/grub/manual/grub/grub.html#Environment-block, >>> which is used to store information from one boot to the next, using >>> save_env and load_env. >>> >>>>> checksummed, and hence I reckon it can become corrupt if power is lost >>>>> in the middle of a write. >>>> >>>> What about the other blocks? >>> >>> In theory, there is only one block, because it is written in-place, >>> directly on disk, without changing any other filesystem blocks. Is that >>> what you meant by "other blocks"? >>> >>>>> This is an important safety criterion for us, so we've been thinking of >>>>> developing environment block checksumming as an extension to the >>>>> existing save_env and load_env commands. The most likely approach will >>>>> be to grab X amount of bytes at the end of the block and use these for >>>>> the checksum. >>>> >>>> Could you tell us more about that? >>> >>> The idea comes from U-Boot [1], which uses a dedicated block on a >>> storage device to store data, and uses a CRC32 checksum to make sure it >>> is consistent. The motivation is to be able to detect that the block is >>> corrupt, rather than accepting a block of data that may have incorrect >>> data in if a write was interrupted midway by a powerloss. You can read >>> more about it in the link. >>> >>> [2] https://www.denx.de/wiki/DULG/UBootEnvVariables >> >> I am OK with the idea. However, I think that the feature should have >> a kind of switch to turn it off/on. At first sight it looks that new >> environment variable is sufficient for it. > > And/Or an argument for save_env/load_env...
Yes, I'm fine with either. How about a variable that determines the default, and you can override it with flags? -- Kristian _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
