[sldev] How Far For Security?

Strife Onizuka blindwanderer at gmail.com
Sat Jun 21 23:32:23 PDT 2008


On Sat, Jun 21, 2008 at 9:25 PM, Argent Stonecutter
<secret.argent at gmail.com> wrote:
> And I'd really like to see how you are proposing SL request a direct
> disk-to-GPU transfer without writing your own driver.

*sigh*
You couldn't go straight from disk to GPU. There is no interface that
connects the GPU to the disk. What you would do is write your program
to make the appropriate requests to read a file into memory. The disk
drive would be told where to read, and to use DMA to write the data
directly to an already allocated memory range (the North Bridge would
route the incoming data straight to memory). Once it was in memory the
program would then tell the GPU what memory range to read and how to
treat that range. The GPU would then request that memory and the North
Bridge would send it along, again bypassing the CPU. Now to confuse
things, in new CPU's (made in the last couple years) the memory
controller has been integrated into the CPU though it is still
separate from the actual part of the CPU that executes instructions.
All of this is cleverly hidden and negotiated by the operating system
and the BIOS; it's done this way so the programmer never need get
their hands dirty with hardware specific code, that has been taken
care of by the hardware manufacturers and operating system developers.
By having the hardware properly obscured by a common API the
programmer can write portable code with limited worry about the
hardware the software is going to run on.

This problem has already been solved, it's pretty much a non-issue.

http://en.wikipedia.org/wiki/Northbridge_(computing)


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