[coreboot] SPD binaries in coreboot

[Sheng-Liang Song]

FYI:
I used put spd data in a stand alone C source code so that I can edit with
vi directly.

unsigned char global_spd_data[256]  = __attribute__ ((section("spd_data")))
{
0x??, 0x??, ...
};

Note: I also put spd_data in the spd data section that is the end of my
binary xloader code.
I can easily edit with bvi editor too.

https://en.wikipedia.org/wiki/Serial_presence_detect


On Fri, Oct 23, 2015 at 11:35 AM, Aaron Durbin <adurbin at google.com> wrote:

> This one's for Ron.
>
> On Fri, Oct 23, 2015 at 10:32 AM, ron minnich <rminnich at gmail.com> wrote:
> > Build the tool in 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>
> 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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-- 
Sheng-Liang Song | Software Engineer | ssl at google.com | 650-537-5017
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