[coreboot] FILO creating filo.conf
c-d.hailfinger.devel.2006 at gmx.net
Tue Sep 16 00:01:06 CEST 2008
On 15.09.2008 23:37, Joseph Smith wrote:
> On Mon, 15 Sep 2008 23:09:01 +0200, Carl-Daniel Hailfinger
> <c-d.hailfinger.devel.2006 at gmx.net> wrote:
>> Still, a custom lightweight fs may be better. Or you reuse the no-erase
>> LAR updating design I created some time ago. The benefit of that LAR
>> variant is that is it backwards compatible (same struct and no code
>> changes in lib/lar.c) and works regardless of block size.
> Hmm, I will look into this also. Is it a part of libpayload?
Not yet. Back then, we were not completely sure about the general
no-erase update design.
However, I created a new design variant which avoids all unnecessary
complexity and is so extremely simple that I wonder why I didn't think
of it earlier. (clear all bits of the first byte of the member name)
The new variant does have one pitfall, though. To reclaim space for a
deleted/updated LAR member, you either need to erase all blocks
"touched" by the member (no problem if filo.conf space is aligned to an
eraseblock beginning) or resort to a more elaborate updating scheme
(Sperrfeuer every 16 bytes of deceased member). (Pay no attention to the
stuff in parentheses, it is a mental note for me.)
I'll write a short design doc with rationale and patches for libpayload
after Oct 1. Please ping me if I forget.
We'll need a write_one_byte_to_flash(u32 addr, u8 byte) function
provided by a flashrom library, though.
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