pm215

78 ms·

841.
by pm215 10y ago
Ah, semihosting; a bit unloved but very useful in some circumstances. Emulators like QEMU also support this interface, which makes it handy for random debug if you're using them as your test/development environment. The Linux kern
842.
by pm215 10y ago
Taking luggage on any mass transit system during rush hour is likely to be a painful experience...
843.
by pm215 10y ago
QEMU always JITs to the host, regardless of target.
844.
by pm215 10y ago
"Pipecleaning" is another term I've heard for that "get the tool workflow sorted" step, I think.
845.
by pm215 10y ago
This is getting perilously close to "attempting to extract performance information from a program running under a simulator/CPU model", which is really tricky to do in a way that gives you results that apply to actual hardwar
846.
by pm215 10y ago
This won't work in the presence of CPU hotplug (which Android uses for power management), because some of the CPUs might not be online when you do it. The API for "tell me this info" is "read the CTR_EL0 register";
847.
by pm215 10y ago
x86 is really the oddity here -- it has its no-explicit-cache-maintenance design because of wanting to maintain backwards-compatibility with self-modifying code that was written for x86 cores that had no caches at all. Almost all other arch
848.
by pm215 10y ago
The state of the art in Linux scheduler handling of big.LITTLE hardware has moved through several different models, getting steadily better at getting best performance from the hardware (wikipedia has a good brief rundown: https:/&#x2
849.
by pm215 10y ago
No, in general Linux migrating processes between cores won't nuke the caches. The hardware's cache coherency protocols between CPUs in the cluster ensures that they are all in sync sufficiently that it's not needed.
850.
by pm215 10y ago
This setting is the cache line size, not the total cache size. You can happily give the bigger cpu more total cache.
851.
by pm215 10y ago
Handling of the case where big and little both want the same thing in their cache should be dealt with by the usual cache-coherency traffic between the CPUs that ensures they don't disagree about what's in their L1 caches (very ha
852.
by pm215 10y ago
Also, if I'm reading the proposed fix in the mono pull request correctly, it doesn't deal with the problem entirely because there's a race condition where the code might start execution on the core with the larger cache line
853.
by pm215 10y ago
For 64-bit ARMv8 (ie AArch64) system registers are in general reorderable; software must provide explicit synchronization (typically via barrier instructions) where it does not want the reordering, except for a few registers which have impl
854.
by pm215 10y ago
Usually you configure the VM to only report CPUID values corresponding to lowest-common-denominator features on everything you might want to migrate to. Then as long as the guest code plays nicely and looks at the CPUID feature flags to see
855.
by pm215 10y ago
Properly configured big.LITTLE clusters should be set up so that all CPUs report the same cache line size (which might be smaller than the true cache line size for some of the CPUs), to avoid exactly this kind of problem. The libgcc code as
856.
by pm215 10y ago
Yes, 'alight' is a verb; listed by the OED as 'alight, v. 1' sense 4b "To descend and settle; (of something in flight) to land. Freq. with on, upon. Also fig.". Citations back to 1330 with ones obviously like t
857.
by pm215 10y ago
On the other hand my general view is that I will always prefer the system install of a language environment, because I know the distro is going to take care of ensuring it works with the distro config, updating it with security bugs and mak
858.
by pm215 10y ago
It's special in that currently getting non-full-time work as a software engineer is pretty tricky (you can often arrange to drop down to part time at your existing company, but getting a job at a new company on non-full-time hours is m
859.
by pm215 10y ago
Stackoverflow to the rescue: http://apple.stackexchange.com/questions/3253/ctrl-o-behavio... This turns out to be because on OSX the terminal driver defaults to throwing away control-O which is rather unhelpful of
860.
by pm215 10y ago
Nope, because I've never used control-keystrokes to do cut-n-paste. I always use (and love) X-style mouse cut-n-paste and hate that there are no good implementations of it on other OSes.
861.
by pm215 10y ago
It's been something I've used for many years, so I really don't recall any more just where I found out about it...
862.
by pm215 10y ago
You can use control-O for that, which does "execute this command as if I pressed enter, then when it's done bring up the following command in command line prompt". So if you have a set of commands to run that are 20 lines up
863.
by pm215 10y ago
Right, and so I've developed the view that the most interesting quality of a static analysis tool is not "how many bugs does it find" but "how many of the things it points out are false positives" and (if you want t
864.
by pm215 10y ago
As you say, now you have two million-line codebases to understand instead of one :-) I think there are things we (the QEMU community) could do to make the learning curve a bit less steep but it is still definitely there...
865.
by pm215 10y ago
If you've ever read the Lions' Book commentary on 6th Edition Unix, you'll notice that many parts of the API as implemented back there are pretty solid -- quality, well designed interfaces that have stood the test of time. Si
866.
by pm215 10y ago
One problem with "take on people for a trial period" is that it's more risky for the candidate too. If you happen to be unemployed then doing a trial-work-period is obviously an improvement on not working at all, but otherwis
867.
by pm215 10y ago
So something I'd like to get advice on is: what do you do negotiation-wise if actually salary is not the thing you care most about? Suppose you (for health reasons or just because you don't need the extra money and like the reduce
868.
by pm215 10y ago
UK experience suggests there's a decent market for delivered groceries: these stats ( http://www.igd.com/Research/Shopper-Insight/Pushing-online-s... ) from 2015 say that 11% of shoppers used online-shopping-wi
869.
by pm215 10y ago
Indeed not, but enquiring into what the in-the-wild de-facto beliefs about behaviour are might help in deciding what the de-jure rules should be changed to, or what a compiler implementation ought to do if it cares about what it does on the
870.
by pm215 10y ago
Heh, I used to own one of these 1000-series machines. In my case it was a unit that had been owned by a company's R&D department, so they'd stripped out a bunch of the "arcade machine" stuff, and all it had when I go

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