[LinuxBIOS] [PATCH] v3: add a check for a termination member

Stefan Reinauer stepan at coresystems.de
Mon Jan 7 14:01:11 CET 2008


thanks for bringing this up.

* Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> [080107 10:40]:
> The bootblock will always be the last member of the lar. We also try to
> fill the lar from the bottom up. That means unless the lar is completely
> full, we will walk an empty are in 16 byte increments. Since we know the
> location of the boot block (top of flash) and we also know we never have
> to lookup or load the bootblock during LB execution, there should be an
> easy way to specify "from here to the beginning of the bootblock there
> will be no file" which is equivalent to "stop searching here".
> The "no file till bootblock" functionality can be implemented in three ways:
> 1. Explicit "stop searching here" marker or lar member.
> 2. Explicit lar member covering the free space.
> 3. List free space somehere in flash.
> Two of these ways fail in practice:
> 3. Listing free space in flash means erasing and/or rewriting that list
> everytime the lar changes. The only reasonable place for such a list
> would be the bootblock and we don't want to touch it during partial reflash.

> 2. Explicit free space covering lar member is fine, but to add any new
> file to the archive, you have to erase the part covered by the exlusive
> space.

I don't think this is such a bit problem. Lar could remove this entry
automatically, and recreate it. This is not more special code in lar
than 1. But I start thinking that those two are pretty much the same in
the end.

What about a linked list in the header? Each file could explicitly point
to the next file. If the pointer is 0 or -1, we stop.

This way we would not lock out the "bootblock" file in our lar search.

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