ebenupton

12 ms·

1.
by ebenupton 2y ago
Cortex-M33 timings aren't documented, but one of our security consultants has made a lot of progress reverse engineering them to support his work on trace stacking for differential power analysis of our AES implementation. I've as
2.
by ebenupton 2y ago
It's a fair comment. Give our VSCode extension a go: the aspiration is to provide uniform developer experience across Linux, Windows, and MacOS.
3.
by ebenupton 2y ago
Yes, several approaches. More here: https://x.com/ghidraninja/status/1821570157933912462
4.
by ebenupton 2y ago
Signed boot. Unless someone at DEF CON wins our $10k bounty of course.
5.
by ebenupton 2y ago
Significant improvements to flat-out power (switcher vs LDO) and to idle power (low quiescent current LDO for retention). Still not a coin-cell device, but heading in the right direction.
6.
by ebenupton 2y ago
Thank you. It's been a major effort from the team, and I'm very proud of what they've accomplished.
7.
by ebenupton 2y ago
It's actually 10 masters (I+D for 4 cores + DMA read + DMA write) versus 6 masters. Or you could pre-arbitrate each pair of I and each pair of D ports. But even there the timing impact is unpalatable.
8.
by ebenupton 2y ago
That's correct. The Arm and RISC-V cores are entirely separate, sharing no logic.
9.
by ebenupton 2y ago
We did look at this, but the AHB A-phase cost of putting a true arbiter (rather than a static mux) on each fabric port was excessive. Also, there's a surprising amount of impact elsewhere in the system design (esp debug).
10.
by ebenupton 2y ago
It has: you can encrypt your code, store a decryption key in OTP, and decrypt into RAM. Or if your code is small and unchanging enough, store it directly in OTP.
11.
by ebenupton 2y ago
It's aliiiiiive!
12.
by ebenupton 4y ago
It is true ROM.
13.
by ebenupton 4y ago
As did Graham Sanderson, whose Easter egg this is.
14.
by ebenupton 5y ago
It is. Both from ( https://direct.raspberrypi.com ), and from various disties. Just shy of 300ku on hand at Farnell today ( https://uk.farnell.com/search?st=rp2040 ).
15.
by ebenupton 12y ago
No - the Model A is still 256MB.
16.
by ebenupton 12y ago
And an additional 256MB (512MB versus 256MB for the Model A).
17.
by ebenupton 13y ago
That's not correct. The code that's been released is for BCM21553, which doesn't have a VPU. There are bits and pieces of VPU assembler in there, but they're unused on the ARM target. The intention is that people port th
18.
by ebenupton 13y ago
You're most welcome. Good times.
19.
by ebenupton 13y ago
Figured you'd get a kick out of this release. Should be enough for people to figure out how Andrew's FFT code works.
20.
by ebenupton 13y ago
The ability to boot a kernel with USB (and thus Ethernet) running. Probably not display in the first instance (we're hella-resource-constrained), but we'd want to add that later on.
21.
by ebenupton 13y ago
Fancy meeting you here :)
22.
by ebenupton 13y ago
BSD-like licenses seem to be the standard for userland graphics libraries. There's a lot of useful stuff in there (for example the shader compiler) that may be of general use elsewhere, and we wanted to make sure people could use it. T
23.
by ebenupton 13y ago
Fingers crossed. I'm most excited about the GPGPU stuff people will be able to do now we've documented the instruction set for the QPU. More on this next week.
24.
by ebenupton 13y ago
:)
25.
by ebenupton 13y ago
I did work on it directly. James (now working solely for Pi as HW director), Gordon (now working solely for Pi as SW director) and I (still working for Broadcom, and for Pi) were members of the VideoCore IV design team. James and I were res
26.
by ebenupton 13y ago
More a moral victory from my PoV. Remember, code that runs in the blob is running on another processor, so not costing you ARM cycles. That's why we've set the Quake fps target much lower than what you can hit with the blob.
27.
by ebenupton 13y ago
Good point. Still hard for me to remember that mobile != ARM these days.
28.
by ebenupton 13y ago
Less than you'd think. Other vendors have improved somewhat, but from often from pretty poor starting points. Jumping a process node is a "brute force" approach: we can all do that. I'm more interested in apples-to-apple
29.
by ebenupton 13y ago
Not quite yet. We're hoping to be able to provide a minimum-functionality blobless world fairly soon.
30.
by ebenupton 13y ago
Yes. See here: http://www.raspberrypi.org/archives/5535 a lot of this work goes upstream.

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