Re: [Yaffs] is the extra info must included in yaffs_ext_tag…

On Thursday 12 April 2012 21:10:57 Ezio Zhang wrote:
> i'm working with yaffs2 the newest version in git. i have some question
> about the one and have some troubles now.
> 1.the newest version add a new structure "summary_header",why and what's
> the benifit?

This is used to implement the block summary feature. The last few (typically
just the last one) chunk in a block is written with the a tags summary which
is just all the tags for the chunks in that block written into a single
chunk.

This allows all the tags to be read in one read, making the boot up faster.

> 2.i'm now migrite yaffs to our system in YDI mode.when i read and write
> data to/from nand flash i don't use packed tags,but when i try to open a
> file,yaffs try to write a new headr to flash,the write is ok,but when the
> summary_tag is adding,the member's of summary_tag is a chaos,i found this
> occured for the function yaffs_pack_tags2_tags_only() ,in this function
> program go to the branch "if (yaffs_check_tags_extra_packable(t)) {" which
> makes the value a fault. so i'm wondering if the extra info member in
> yaffs_ext_tags is a must member?can i remove it?

What do you mean you are not using packed tags?
Why would you want to remove it?

The extra info is stuff that can be packed into the tags if there is space to
do so. If there is never extra info, this data is just read.

It should be fine to always force extra info to zero, but doing that will make
the booting slightly slower.

-- Charles