On Thu, Apr 16, 2020 at 03:02:06PM +0900, Masami Hiramatsu wrote: > Hi Luis, > > On Wed, 15 Apr 2020 06:30:41 +0000 > Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > > Currently the maximum config size size is 32KB and the total key-words > > (not key-value entries) must be under 1024 nodes. Note: this is not > > the number of entries but nodes, an entry must consume more than 2 nodes > > (a key-word and a value). So theoretically, it will be up to 512 > > key-value pairs. If keys contains 3 words in average, it can contain 256 > > key-value pairs. In most cases, the number of config items will be under > > 100 entries and smaller than 8KB, so it would be enough. If the node > > number exceeds 1024, parser returns an error even if the file size > > is smaller than 32KB. Anyway, since bootconfig command verifies it when > > appending a boot config to initrd image, user can notice it before > > boot. > > ``` > > *recommending* bootconfig due to the limitation of cmdline seems > > sensible, however if we advise that.. wouldn't the space for 512 > > theoretical entries full up rather fast? > > Yeah, I think it is easier to hit the node number limitation rather > than fill up the space. However, since the bootconfig supports comments, > if user writes enough readable config file, I think it's probably the > right balance :) > If you think the 512 entries is too small, it is easy to expand it > upto 32K (64K nodes). But it may consume 512KB memory only for the > node (meta) data. Current 1024 nodes consumes 8KB (8bytes/node), so > compared with the max data size (32KB), I think it is a better balance. Yeah, and well at least x86 / x86_64 sets COMMAND_LINE_SIZE to 2048 right now (2 KB), that'd hit the limit of abuse of cmdline pretty fast too. I see no way to scale this reasonably if people abuse syctls on the command line but to use bootconfig and bite the bullet on size, to keep sanity. Luis
