pm215

60 ms·

631.
by pm215 8y ago
Nobody sat down and said "yes, I'll make this nondeterministic". If you look at the wiki page's sampling of different issues -- https://wiki.debian.org/ReproducibleBuilds/Howto#Identified_... -- you
632.
by pm215 8y ago
Google manages to scale up fine in this case -- searching for 'the dragon book' gives the correct answer as its first hit (via wikipedia)...
633.
by pm215 8y ago
Yes, most of us would probably have to check the manpage for three or four of these utility programs to put together something like Rob McIlroy's one-liner from the article. I think this is clearly still more efficient than writing 17
634.
by pm215 8y ago
I had jam roly-poly in our work cafeteria last week -- but you're right that it does have a tinge of the school dinner about it.
635.
by pm215 8y ago
Speaking as somebody who actually ported it (or at least the second-generation "intent/elate") to new platforms, it took more than three days (though you could probably get to "hello world" in three days or so if yo
636.
by pm215 8y ago
Those instructions are not using QEMU to emulate the Pi. They tell QEMU to emulate an entirely different piece of hardware (the versatilepb board) and run the raspbian userspace on it. You certainly won't be able to test any code for t
637.
by pm215 8y ago
c should not be a char or unsigned char, because the return type of getchar() is "int". If you put it into a char-width variable then you lose the distinction between EOF (which is -1) and the byte 0xff. Getting the type of '
638.
by pm215 8y ago
I meant that it doesn't affect it in the sense that it doesn't change the way the cache behaves or ask it to flush or invalidate any of its contents. You can have a pipelined CPU which needs the barrier insns but which has no cach
639.
by pm215 8y ago
The post seems to be slightly confused about the Arm DSB and ISB instructions. These don't affect the caches at all -- they are barriers, which affect ordering and pipelining. DSB says "don't go any further until all memory
640.
by pm215 8y ago
That's not 'more relaxed' pronunciation, it's a set of different accents (not a phenomenon unique to English). People don't arbitrarily mix and match between them, and any particular accent preserves enough vowel di
641.
by pm215 8y ago
I think part of the problem here is that if the only thing running on $MINORITY_PLATFORM is your CI loop, then when it does find an issue it's going to be harder for the devs to fix, and it's never going to get the breadth of cove
642.
by pm215 8y ago
Yes, I can definitely recommend stgit if what you're doing is basically "maintain this stack of patches". It's much more user-friendly as an UI for doing that than raw git rebase, though of course you can achieve the sam
643.
by pm215 8y ago
This would have been gcc 5.4.0, as shipped by Ubuntu 16.04. Certainly it's possible that newer gcc do better, but from my point of view if they started out with something that breaks the debug illusion it indicates that their definitio
644.
by pm215 8y ago
That is for arm32 userspace binaries being run under an arm64 kernel, and applies only to the handful of instructions which in Armv8 still generate alignment faults. With an arm32 kernel you could configure the kernel to fix those up as wel
645.
by pm215 8y ago
QEMU briefly used -Og for its debug build setting, but switched back to -O0, because in practice using -Og results in a lot more situations where gdb just says "<optimised out>" rather than being able to tell you the values
646.
by pm215 8y ago
Note that since banks have to make a profit, if they're not doing it via an annual current account fee then they're doing it via setting interest rates and one-off charges for things like going overdrawn. What consumers will put u
647.
by pm215 8y ago
I took part for the first time this year, as an exercise in learning Rust (I have got up to day 20 so far). It's been pretty good for moving from "I sort of know this language" to being a bit more comfortable with it just by
648.
by pm215 8y ago
A minor nit, but memory tagging is in ARMv8.5, not 8.3.
649.
by pm215 8y ago
Why would it be "extreme" inertia to still be using Firefox? If it's never felt like it's failing to do the job of being a web browser, then not switching is inertia, sure, but it's not extreme...
650.
by pm215 8y ago
Big-endian arm is pretty rare -- it's basically a niche requirement for markets like embedded network hardware where there is a lot of pre-existing code that assumes big-endian because it used to be run on m68k or mips. Most network pr
651.
by pm215 8y ago
The syscall(5) manpage documents the Alpha syscall abi as passing arguments in a0,a1,a2,a3,a4,a5 which would suggest so. (MIPS o32 is the only listed one which is a bit oddball: you can only pass 4 args in registers and then use stack for 5
652.
by pm215 8y ago
I think for setuid in particular the right fix is for the kernel to provide a new syscall that operates on the whole process. The current hoops that glibc has to jump through with signals are complicated (and maybe racy? it's been a wh
653.
by pm215 8y ago
Do you have a sketch of how that would work? It seems plausible but I haven't thought through the details. Issue 1373 suggests a perf counter of failed-SC events and looking at "branches taken - failed_SC", which I'm def
654.
by pm215 8y ago
rr has an "extended technical report" at https://arxiv.org/pdf/1705.05937.pdf which explains the principles it uses. In general they are inherently rather complicated -- in order to get to anything resembling
655.
by pm215 8y ago
The upstream issue with discussion about Arm support is https://github.com/mozilla/rr/issues/1373 -- the underlying problem is that rr's design assumes that if you execute N instructions you'll alwa
656.
by pm215 8y ago
If you use a Cortex-M0 (v6M) then there are only 60 or so instructions total...
657.
by pm215 8y ago
The problem is that it isn't really something the project can fix -- the problem is with the antivirus, whose vendors aren't very responsive. See for instance the PuTTY devs' todo list item about virus false-positives: https
658.
by pm215 8y ago
The insn is definitely js-specific though. The architecture has int-float conversion insns already which work fine for the purposes of almost all languages (dynamic or not); but js requires some specific oddball semantics which this new ins
659.
by pm215 8y ago
QEMU hasn't got round to pointer-authentication yet either, so that's pretty good going. I like the "fuzz-test one implementation against another" approach. That's quite similar to how we test QEMU against real har
660.
by pm215 8y ago
In practice, the bad guys are not getting credit card numbers by monitoring unencrypted plain text email connections. They're doing it by getting the information in bulk straight out of databases at the destination (either by hacking o

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