lgeek

13 ms·

61.
by lgeek 12y ago
I'm with you on this one. After seeing this running at 15-20 fps, my reaction was that web technologies have finally been shoehorned in a place where they can almost provide the same experience as 15 year old native games, while runn
62.
by lgeek 12y ago
> Zeroed memory should not be particularly expensive on modern machines, because we have a lot of parallelism available to zero it off working threads. It must be nice living a world where energy is free, you have unlimited cores and unb
63.
by lgeek 12y ago
Many of the capabilities described in the article are just hardware features which don't need any control from application developers, but their effectiveness can be improved if the developers are aware of them (e.g. caches, TLBs). Oth
64.
by lgeek 12y ago
The added electronics just rest against the adapter's boards: http://samy.pl/keysweeper/testingsize.jpg . This looks quite unsafe because of reduced clearances. It has a chance of either exposing HV on the LV (USB
65.
by lgeek 12y ago
If you can set a chromebook to developer mode, it's quite simple to then sign your own images containing either another bootloader or a custom kernel. The only annoyance from my point of view is that vboot images don't seem to sup
66.
by lgeek 12y ago
Chromebooks can also run ChromeOS in a window on GNU/Linux* , which is rather more useful for ocassional Netflixing mixed with more productive use. * probably a violation of the EULA
67.
by lgeek 12y ago
They have a GSM network too: http://events.ccc.de/congress/2014/wiki/Static:GSM
68.
by lgeek 12y ago
I haven't used Radxa SBCs, but I did some development for RK3188 GNU/Linux support half an year ago. At the time the hardware video encoders and decoders were not supported on GNU/Linux, but worked ok on Android (with libstag
69.
by lgeek 12y ago
However, mmap and the functions which rely on it will return MAP_FAILED/NULL if no gap large enough is found in the virtual address space or if you've used MAP_FIXED and the area isn't free. If you don't check for errors
70.
by lgeek 12y ago
On the systems I've seen, brk makes a lazy allocation, i.e. it doesn't allocate physical memory until you write to a page.
71.
by lgeek 12y ago
Yeah, you were right. I've checked and it seems the GCC version I'm using is inlining memcpy calls if it can statically determine the size argument and if the size is lower or equal to 64 bytes.
72.
by lgeek 12y ago
What compilers are you thinking about? I've never seen GCC inlining and specializing a call to memcpy, it just calls the generic (but optimized) implementation in the standard library.
73.
by lgeek 12y ago
> Has a simple mapping to the underlying hardware? That stopped being true three decades ago. I've seen this claim repeated a few times in the thread and I still have no idea what it means. For medium levels of optimisation it'
74.
by lgeek 12y ago
Not ewww , it's one of the more interesting developments (well, technically a revival) in computer architecture from the industry. I just wish they'd 1) document their architecture and 2) allow access third party access to the ba
75.
by lgeek 12y ago
It's virtual addressing, the loader maps the image at whatever address is specified (with some restrictions).
76.
by lgeek 12y ago
The 64-bit Tegra K1 doesn't run ARMv8 code natively. It's a proprietary VLIW architecture with an undocumented (AFAIK) ISA. It executes ARMv8 using a firmware-level dynamic binary translator, similarly to how Transmeta processors
77.
by lgeek 12y ago
Even if the JTAG pins are brought out, the hardware is a proprietary NVIDIA architecture, you wouldn't have any development tools for it. I suppose they might use the DBT firmware to allow direct debugging of the ARM code, but I don&#x
78.
by lgeek 12y ago
Link at the correct address so there's 1MB between the end of the application image and the bottom of the stack. Allow the linker to load the shared libraries (or just link statically) and then use mmap to fill the rest of the virtual
79.
by lgeek 12y ago
> Its a symptom of doing really ugly things with the stack Yes, that's spaghetti code. In general I strongly recommended to write assembly functions which follow the platform's ABI (I'm a TA for a course using assembly pro
80.
by lgeek 12y ago
It may be the same in the sense that hypervisors don't explicitly limit it, but on a multicore host you're sharing memory bandwidth with the other guests, in the common(?) case when the host has more cores than a guest. You can al
81.
by lgeek 12y ago
Linking order will affect code and static data order and cache alignment in turn. Similarly, environment variables are pushed on the stack by the kernel. Their size will affect alignment of application data on the stack. Maybe there are oth
82.
by lgeek 12y ago
For prototyping you can also solder BGAs with any hot air rework station. Even if you don't already have one, Atten 858D only costs around $60. Here's an example (not my video): https://www.youtube.com/watch?v=L8EW
83.
by lgeek 12y ago
I think it's using the analog audio hardware, similarly to this project.
84.
DieHard: An error-resistant memory allocator for Windows, Linux, and Mac OS X(github.com)
64 points by lgeek 12y ago|17 comments
85.
by lgeek 12y ago
I would suggest reading the jemalloc paper [0]. The main improvements compared to phkmalloc are: * improved cache locality * reduced false sharing * use of multiple arenas for reduced lock contention [O] http://people.freebsd.org
86.
by lgeek 12y ago
I really doubt there's any data size for which sort + binary search is going to be faster than linear search. The former has higher complexity (so it's going to be slower for large inputs) and more expensive operations (so it will
87.
by lgeek 12y ago
It's been a while since I've used it and it turns out it's a first generation Samsung Chromebook (XE303). I don't remember having any WiFi-related issues. The source code used to build the kernel for ChromeOS should be a
88.
by lgeek 12y ago
You can boot your own kernel directly to a GNU/Linux rootfs. If you need more space, high speed SD cards work quite nicely.
89.
by lgeek 12y ago
Tianocore EDK2, which they plan on using, is the reference UEFI implementation and is BSD-licensed. ARM actually develops and maintains the ARM-specific parts of the implementation.
90.
by lgeek 12y ago
There's very little ARM hardware in a laptop form factor in general, none of it is ARM64, and the ones that exist are mostly chromebooks, so maybe not the best build quality.

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