christina_b

6 ms·

1.
by christina_b 8y ago
Regular LTO for large sized projects (think Chromium sized), in my experience is by far the biggest bottleneck in the build process. It's partially the reason so much is being invested into development and improving parallel linking as
2.
by christina_b 9y ago
I was pretty sure TouchMe was BetaMonkey's new nick, I don't think it was Ntoskrnl (MalwareTech). From what I've heard TouchMe continued support of his drone's users until he dissapeared without a trace. This was so long
3.
by christina_b 9y ago
BetaMonkey/TouchMe was in fact the person I was referring to who was providing support for his botnet drone builder until he dissapeared with no trace at a later date. Just could not recall the nick at the time of making my original po
4.
by christina_b 9y ago
I may be totally off base here but IIRC, before he ran MalwareTech and was a whitehat, he participated (and was an op) in fairly "shady" IRC channels, with his oldest nick I can recall being `Ntoskrnl`, dedicated to malware and ma
5.
by christina_b 10y ago
Hm, I may have been wrong, would be nice to have someone who owns one of these boards to verify that: 1). The first stage bootloader doesn't require signing. 2). The first stage bootloader starts in EL3 mode (ie. BootROM doesn't e
6.
by christina_b 10y ago
All modern ARM chips support secure mode, it's a set of modes, in AArch64, we colloquially call them EL3 (Exception level 3, highest privilege level above EL2, the hypervisor level). Most ARM cores start in secure supervisor mode, whic
7.
by christina_b 10y ago
See my other comment about Allwinner, but basically my biggest issue is that they lock down their bootloader with signing and do not allow you to execute code in EL3/Secure mode without exploits.
8.
by christina_b 10y ago
If a "development" board does not let me run my own code in EL3 (Secure monitor mode), I'm not buying it, as simple as that. A lot of boards that use Allwinner chips will use a signed bootloader that exits secure mode before
9.
by christina_b 10y ago
>All of these could probably have been fixed with minimal support from broadcom (and a bit more open thinking from them during the design). Support from Broadcom is unlikely to fix it, the BCM283x family of SoCs are just a huge mess an
10.
by christina_b 10y ago
>drivers handling graphics Actually that's open and mainlined now, there are DRM drivers for BCM285x family but they rely on mailbox interfaces for power and clock management.
11.
by christina_b 10y ago
Currently it sleeps and waits for a mailbox interrupt after which it acks it and goes back to sleep. We're planning on using the interface to load a second stage firmware that would emulate the closed source firmware's power/
12.
by christina_b 10y ago
>No, Broadcom is quite unique in requiring blobs to boot. Yes precisely, so we offer an alternative to those blobs that allows you to boot ARM without needing a closed-source firmware.
13.
by christina_b 10y ago
We have considered it, however, because there's still a need for a firmware, the first stage bootloader and the firmware itself are using a common driver framework, it just makes things easier. Besides, the firmware will later run an R
14.
by christina_b 10y ago
binutils/GCC, have Julian to thank for his wonderful toolchain: https://github.com/puppeh/vc4-toolchain
15.
by christina_b 10y ago
>unlocking the unique video core to get anywhere near there We actually have documented most vector instructions of VC4 and Julian's toolchain supports pretty much all documented ones, so the toolchain we have is pretty close to w
16.
Blobless Linux on Raspberry Pi(crna.cc)
291 points by christina_b 10y ago|108 comments
17.
by christina_b 10y ago
Oh, which aspects?
18.
by christina_b 10y ago
Actually, the bulk SDRAM/ARM work was done by me in the space of around month (though I only ARM to finally work three days ago with Herman's help). You could run Linux on ARM using this but you would need to write some more drive
19.
by christina_b 10y ago
Yes if you can implement high performance video codecs using pretty much undocumented vector instructions of the VPU, you are welcome to do so.
20.
by christina_b 10y ago
It wasn't a leak, Broadcom publicly released all this code a while ago to aid the making of an open source GPU driver. All this has been licensed under 3-Clause BSD license and distributed by Broadcom themselves. There's no point
21.
by christina_b 10y ago
Yeah, I saw, I haven't looked at it in detail but I think yours probably works better than mine since you did comprehensive testing. My only tests involved compiling my own firmware code, but from what I can tell, it works well, I have
22.
by christina_b 10y ago
I outlined what I did in another comment, here's a log from my current firmware: http://crna.cc/vpu_bootlog.txt I think I'm on the right track but I don't have ARM working yet, most likely due to clock miscon
23.
by christina_b 10y ago
VC4 itself doesn't have a MMU per se, it supports very limited memory remap (like PPC BATs) so running a conventional kernel on it is probably not possible. Best bet would be to port an RTOS to it, but my current plan for my firmware p
24.
by christina_b 10y ago
Don't think I can without first implementing MC emission and running LLVM unit tests on it.
25.
by christina_b 10y ago
Yeah I looked at it, my firmware mostly just aims at bringing up enough stuff to be able to boot ARM, which is essentially just: - Setting up exception vectors and enabling exceptions - Reclocking VPU from PLLC - UART initialization
26.
by christina_b 10y ago
This isn't the same, the document in question relates to the QPU ISA. The VPU ISA hasn't been officially documented but there were many projects that involved reverse engineering it. The VC4 ISA is documented here: https:/&#
27.
by christina_b 10y ago
To elaborate, I made this to develop an open source VPU side bootloader for Raspberry Pi because I was unhappy with the state of other C compilers targeting VC4 (I explained why in my blog). I haven't had the time to work on my firmwar
28.
LLVM for VideoCore4 (Raspberry Pi VPU)(github.com)
5 points by christina_b 10y ago|0 comments
29.
Improving LLVM for VideoCore4 (Raspberry Pi VPU): Part 1(crna.cc)
2 points by christina_b 11y ago|0 comments
30.
by christina_b 12y ago
Strange, it doesn't happen for me.

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