[Cerowrt-devel] [Make-wifi-fast] [bufferbloat-fcc-discuss] arstechnica confirmstp-link router lockdown
chromatix99 at gmail.com
Tue Mar 15 05:38:42 EDT 2016
> On 15 Mar, 2016, at 05:47, dpreed at reed.com wrote:
> SoCs often have multiple functional units on the same die. For radios that allows for a pipeline. You can limit what an EPROM will accept with a crypto signature.
> This is common stuff.
As an example of this, AMD’s APUs and GPUs require several different firmware blobs to bring up their 3D capabilities. The on-board BIOS supplies only what is necessary for basic SVGA framebuffer mode, which the operating system can use as a stopgap until the drivers are installed.
In Linux, these firmware blobs are identified by the IP block’s codename. Most APUs and GPUs require a SUMO or SUMO2 blob to bring up the RAMDACs, and a separate GPU-specific blob (VERDE for my 7770) for the graphics engine itself, which takes up a much larger portion of the die.
I’m not sure whether these blobs are signed in AMD’s system, but they could be. Their APUs have a Cortex-A5 based “secure processor” which could in principle be tied into the firmware-loading process, and probably has its own secure ROM. A Cortex-M microcontroller core and ROM to do the job on a GPU would be tiny.
- Jonathan Morton
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