Just a little more than a week after AMD openly released R600/700 GPU code to begin development of an open-source 3D driver for their ATI Radeon HD 2000/3000/4000 hardware, a disassembler and table dumper for their video BIOS abstraction layer has been released to developers. This tool called AtomDis was used early on in the development of the RadeonHD driver by Novell and is now being released under the GNU GPLv2 license to assist interested open-source developers or act as an instrument to those learning about graphics processor programming.
AtomDis serves as a BIOS disassembler and table dumper to the AtomBIOS, which is the video BIOS abstraction layer used on ATI GPUs since around the R400 series. The AtomBIOS and debate over its usage was what originally caused the two competing drivers (xf86-video-ati and xf86-video-radeonhd) for the same hardware up until the RadeonHD driver ended up adopting AtomBIOS for use in supporting newer ATI GPUs as they were under pressure from Advanced Micro Devices.
Previously AMD released an open-source AtomBIOS parser for use by the X.Org graphics drivers. In July of last year they released a new AtomBIOS parser that would be ideal for entering the mainline Linux kernel in order to provide ATI kernel mode-setting support. Besides that, however, the low-level code to AtomBIOS has not been open-sourced and because of that was one of the reasons it was initially rejected by the Novell developers working on the RadeonHD driver. In 2007 there was a project started by an independent X.Org developer to create an open-source ATI BIOS by reverse-engineering AtomBIOS, but that project hasn't materialized.
Running AtomDis just requires the header file from the AtomBIOS parser source-code found in the RadeonHD driver and then a video BIOS image. The video BIOS off ATI GPUs can be dumped using the rhd_conntest utility that is also found within the xf86-video-radeonhd repository. When executing AtomDis the AtomBIOS image must be loaded along with a command to dump information on AtomBIOS, list all AtomBIOS tables, create a hex dump, data table dump, command table disassembler, table disassembler, and the last option is a full sanitized dump. Contained in AtomBIOS tables is data for PowerPlay, LVDS details, firmware information, GPU initialization, and many other areas of GPU programming.
For developers or those with any other interest in learning about AtomBIOS can use Git to clone git://people.freedesktop.org/~mhopf/AtomDis.
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