On 02/18/14 20:17, Gabriel L. Somlo wrote:
On Tue, Feb 18, 2014 at 11:21:33AM +0100, Gerd Hoffmann wrote:
Using Fedora 20 live, I collected the SMBIOS table from the guest using "dmidecode --dump-bin", with the unpatched SeaBIOS (dmidecode_pc.bin), SeaBIOS with my patch applied (dmidecode_mac.bin), and again with unpatched SeaBIOS but with "-smbios file=dmidecode_mac.bin" on the QEMU command line (dmidecode_cmdline.bin).
[...]
However, when I compare unmodified SMBIOS against what I get when supplying the patched binary table via command line, I get this:
$ diff dmi_pc.txt dmi_cmdline.txt 2c2
< Reading SMBIOS/DMI data from file dmidecode_pc.bin.
Reading SMBIOS/DMI data from file dmidecode_cmdline.bin.
4c4
< 10 structures occupying 298 bytes.
11 structures occupying 657 bytes.
108,109c108,120 < Handle 0x7F00, DMI type 127, 4 bytes
< End Of Table
Handle 0x5F4D, DMI type 95, 83 bytes Unknown Type Header and Data: 5F 53 4D 5F 32 1F 02 04 4B 00 00 00 00 00 00 00 5F 44 4D 49 5F D2 46 01 20 00 00 00 0B 00 24 00 00 18 00 00 01 02 00 E8 03 00 08 00 00 00 00 00 00 00 00 04 01 00 FF FF 42 6F 63 68 73 00 42 6F 63 68 73 00 30 31 2F 30 31 2F 32 30 31 31 00 00 01 1B 00 Strings: ....
Invalid entry length (0). DMI table is broken! Stop.
No Type 2, no extra fields for Type 17, and a corrupt table to boot.
I had tested this qemu interface with my OVMF SMBIOS patches. It works. (I used a Type 3 table.)
The problem in this case is that you can't just pass in a raw dump from dmidecode. You need to prefix it with "smbios_header":
struct smbios_table { struct smbios_header header; uint8_t data[]; } QEMU_PACKED;
struct smbios_header { uint16_t length; uint8_t type; } QEMU_PACKED;
You need to set "type" to 1 (SMBIOS_TABLE_ENTRY), and set "length" so that it covers the entire "smbios_table" struct (ie. both header and payload, where payload is your SMBIOS table). "length" is little endian.
Laszlo