[coreboot] [Bug?] 3 different bytes in VGAbios after upgrade to coreboot

Rudolf Marek r.marek at assembler.cz
Tue Jun 9 20:11:26 CEST 2015


Hi all,


Dne 7.6.2015 v 02:12 Vladimir napsal(a):
> Thank you very much for solving this riddle!
> And one more question for Rudolf: please tell, are you using atomDis
> utility to disassemble atombios into C code? Or there are some other
> special tools, which probably have more recent versions? (latest version of
> atomDis is already 4 years old...)

I think there was some effort to make VGA BIOS from scratch. I think the guys
used a script to rewrite it to C. I don't remember anymore.

Thats all I know,

Thanks
Rudolf

> 
> On 3 June 2015 at 20:27, Rudolf Marek <r.marek at assembler.cz> wrote:
> 
>> Hi all,
>>
>> First byte after IBM is usually a checksum. So in fact only two bytes
>> differ.
>> Now you may ask what it is... and it is a IOBASE :)
>>
>> typedef struct _ATOM_ROM_HEADER
>> {
>>   ATOM_COMMON_TABLE_HEADER sHeader;
>>   UCHAR> uaFirmWareSignature[4];    /*Signature to distinguish between
>> Atombios
>> and non-atombios,atombios should init it as "ATOM", don't change the
>> position */
>>   USHORT usBiosRuntimeSegmentAddress;
>>   USHORT usProtectedModeInfoOffset;
>>   USHORT usConfigFilenameOffset;
>>   USHORT usCRC_BlockOffset;
>>   USHORT usBIOS_BootupMessageOffset;
>>   USHORT usInt10Offset;
>>   USHORT usPciBusDevInitCode;
>>   USHORT usIoBaseAddress; <---------------this changes
>>
>> I guess IOBASE of PCI device changes also...
>>
>>   USHORT usSubsystemVendorID;
>>   USHORT usSubsystemID;
>>   USHORT usPCI_InfoOffset;.
>>   USHORT usMasterCommandTableOffset; /*Offset for SW to get all command
>> table
>> offsets, Don't change the position */
>>   USHORT usMasterDataTableOffset;   /*Offset for SW to get all data table
>> offsets, Don't change the position */
>>   UCHAR  ucExtendedFunctionCode;
>>   UCHAR  ucReserved;
>> }ATOM_ROM_HEADER;
>>
>> You can use atomDis to dump it I guess (Did not check if it dumps also the
>> header.
>>
>> Thanks
>> Rudolf
>>
> 
> 
> 



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