[coreboot] SPD binaries in coreboot

Alex G. mr.nuke.me at gmail.com
Sat Oct 24 00:22:28 CEST 2015

On 10/23/2015 08:32 AM, ron minnich wrote:
> Build the tool in go.

Not everybody knows or wants to learn go.

> It's trivial. If you have an idea how it ought to
> work I can set it up in the playground in a few minutes.
> ron
> On Fri, Oct 23, 2015 at 8:24 AM Patrick Georgi <pgeorgi at google.com
> <mailto:pgeorgi at google.com>> wrote:
>     Hi,
>     Some mainboards come with soldered-on memory without SPD ROM. For
>     these, we carry the SPD data in coreboot.
>     Currently, they're stored in a hexdump format that is then converted
>     to binary at build time. The various mechanisms of doing so fail on
>     some platform or another:
>      - "echo -e -n $stuff" isn't well-liked by some shells (emits "e -n
>     $stuff")
>      - "printf '\x42'" isn't well-liked by some shells (or /usr/bin/printf
>     tools) that don't support hexadecimal formats
>      - "printf '\0377'" isn't well-liked by some non-conforming, but
>     existing shells
>      - xxd -rg1 $file > $file.bin requires xxd, which comes with vim and
>     may just not exist
>     I see essentially two ways out of this, before we can start reducing
>     duplication across the tree in that area:
>     We could build our own tool to parse hex files and dump binary, or we
>     could ship SPD data as binary from the start (and only have to
>     concatenate them).
>     The second option has the appeal of being much simpler (and there
>     isn't really a "preferred form" for editing SPD data that I'm aware of
>     - is there?), but looks icky at a glance because it's binary (but it's
>     really just as impenetrable as the equivalent hexdump).
>     So what do these files contain? Parameters (as in: facts) about the
>     hardware's size, layout, and timing, and a bunch of vendor/model
>     identifier strings.
>     So, is there a third option that I'm missing? Other opinions?
>     Patrick
>     --
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