[coreboot] Need new type for CBFS

[Thomas Jourdan]

Hi guys

I was playing with CBFS and I found an strange behavior. There are
actually 4 types of files in a CBFS rom : stage, payload, option rom and
NULL. The latest is used when we don't care of the component type.

I guess if we want to embed a logo, payload specific data or other
stuffs, we must use this NULL type. The problem is that the free space
in the rom also has a NULL type. In the fs.c file, rom_alloc function,
the code searches for a cbfs_file with type == CBFS_COMPONENT_NULL, and
if it is large enough, it will store the file in it. Otherwise, it
continues until finding a large enough NULL type file.

If you want to add more than one NULL type file, it will work as long as
you insert them from the smallest to the largest. Otherwise the NULL
type file you are adding will overwrite an existing one.

Example to reproduce the behavior :
- create a dummy bootblock
    dd if=/dev/urandom of=bootblock.rom bs=64k count=1
- create a test cbfs archive
    ./cbfstool test.rom create 524288 65536 ./bootblock.rom
- create 2 dummy files (64 and 128 KB)
    dd if=/dev/urandom of=dummy64K bs=64k count=1
    dd if=/dev/urandom of=dummy128K bs=64k count=2

Now, if I add my files from the smallest to the largest :

./cbfstool test.rom add dummy64K dummy64K free
./cbfstool test.rom add dummy128K dummy128K free
./cbfstool test.rom print
test.rom: 512 kB, bootblocksize 65536, romsize 524288, offset 0x0
Alignment: 16 bytes

Name                           Offset     Type         Size
dummy64K                       0x0        free         65536
dummy128K                      0x10030    free         131072
                               0x30060    free         261976

Everything works fine. But if I had the 128K file first, then the 64K
file :

./cbfstool test.rom add dummy128K dummy128K free
./cbfstool test.rom add dummy64K dummy64K free
./cbfstool test.rom print
test.rom: 512 kB, bootblocksize 65536, romsize 524288, offset 0x0
Alignment: 16 bytes

Name                           Offset     Type         Size
dummy64K                       0x0        free         65536
                               0x10030    free         65496
                               0x20030    free         327560

I think it is required to make the distinction between a user or custom
type for embedded data, and the free space.

What do you think ?

Regards,
Thomas

Bonus question : shouldn't the cbfs code (to parse, find a file...) be
added to the libpayload ?