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epilys commented on A deep dive into QEMU: The Tiny Code Generator (TCG), part 1 (2021)   airbus-seclab.github.io/q... · Posted by u/costco
epilys · 8 days ago
(2021).

Keep in mind that TCG API and internals have no stable guarantees, so if you cross-reference with current QEMU code you are bound to find differences.

epilys commented on Writing a Hypervisor in 1k Lines   seiya.me/blog/hypervisor-... · Posted by u/ingve
anchovy_ · 3 months ago
Tangentially related: can anyone here recommend some good resources (preferably even books) on hypervisors? Back in university we got a brief introduction into the topic but I was always interested in learning about it more in depth.
epilys · 3 months ago
Seconding the other comments that recommend architecture manuals and guides.

For Aarch64, Arm's official guide is pretty good https://developer.arm.com/documentation/102142/latest/

epilys commented on Emulating aarch64 in software using JIT compilation and Rust   pitsidianak.is/blog/posts... · Posted by u/todsacerdoti
bonzini · 4 months ago
Yep, vm-memory needs pretty large changes to the crate itself but fortunately they're already in progress to add IOMMU support to the virtio and vhost crates. Probably there will be an API break but with old and new crates able to talk to each other so you don't need a flag day.

I am curious if you get to DMA before or after QEMU, and if before what your API will look like.

epilys · 4 months ago
Very little free time unfortunately... Haven't spent many hours on this project.
epilys commented on Emulating aarch64 in software using JIT compilation and Rust   pitsidianak.is/blog/posts... · Posted by u/todsacerdoti
lionkor · 4 months ago
This is a common issue in the Rust world, I think, but I wanted to point it out; I was looking forward to seeing someone build a little minimal JIT for this.

Instead the author uses Cranelift[1] and binja to solve the two interesting problems here.

While cool, I'm not sure if that's interesting enough to read through in its entirety. I use libraries all day every day, but is it the hacker spirit to make your entire project glue-code for libraries that do the thing you claim to do?

It's maybe more philosophical than anything.

1: https://cranelift.dev/

epilys · 4 months ago
Writing a JIT and a disassembler are completely separate topics than emulating a system, don't you agree? :D (The article only talks about structuring a system emulator.)

The disassembler is my next step, since it's the easiest to tackle. Swapping binja for a custom solution on the existing code would be relatively straightforward.

The JIT is a completely different beast, it's essentially the IR -> codegen steps of a compiler (meaning without parsing, syntax/lexical analysis, object generation). Seeing as I wanted to target both x86_64 and aarch64 hosts, using an existing solution would get me started faster before I eventually write my own.

My plan is to split the JIT backends and keep cranelift for x86_64 support, but have my own aarch64 JIT also.

You have to pick your battles and assign priorities, you cannot re-invent everything at once.

(Author here)

epilys commented on Emulating aarch64 in software using JIT compilation and Rust   pitsidianak.is/blog/posts... · Posted by u/todsacerdoti
bonzini · 4 months ago
Reusing the work-in-progress QEMU code is awesome!
epilys · 4 months ago
Yes! I also started with using vm_memory traits in the beginning but delayed it till I refactor my memory subsystem. When we get that in upstream QEMU it might be possible to share this implementation as well as future devices.
epilys commented on QEMU 10.1.0   wiki.qemu.org/ChangeLog/1... · Posted by u/dmitrijbelikov
ducktective · 4 months ago
Awesome tech!

It's not possible to run an android VM on QEMU right? As in, is it officially supported? (I know about Waydroid)

epilys · 4 months ago
Yes, it's possible and supported. QEMU can emulate an aarch64 system, and Google provides aarch64 Android builds for virtual machines specifically, called "Cuttlefish". Search for keywords "Android Cuttlefish QEMU" for instructions.
epilys commented on The Unix-Haters Handbook (1994) [pdf]   simson.net/ref/ugh.pdf... · Posted by u/oliverkwebb
epilys · 4 months ago
The only book I have that came with a barf bag. More books should do this.
epilys commented on Greek Particles (1990)   specgram.com/Babel.I.2/07... · Posted by u/veqq
YeGoblynQueenne · 8 months ago
Satirical intent aside it's true that the way some ancient writers use particles makes it much harder to read and understand their writings, to me at least. To be clear, I'm a native Greek speaker and I can comfortably read back to at least the Koine Greek of the Gospels. But I've tried Xenophon in particular, who's mentioned in the article and I remember it being hard going, to the point I gave up and continued with the modern Greek translation (I had an edition with the ancient and modern text on opposite pages).

I distinctly remember being very confused about the spray of particles interjected between nouns and verbs, and trying to shut out the noise of the particles to be able to parse a sentence. I probably got a headache.

The problem is that, the meaning of "ενταύθα", "ουν", "ον", "γε", "δε", "ην", etc may be well known if you take them as individual words, but when you string them together they're apparently trying to say ... something. And that something is opaque and incomprehensible, like an ancient joke for which you have no context.

epilys · 8 months ago
I agree it depends on the writer and their cultural and educational background. Another example is Thucydides (which as also a native Greek speaker, find funny that anglophones pronounce as Thoo-see-dee-dees, but I digress). Thucydides was considered even in eras closer to him than to as as too abstract/verbose.

Meanwhile Plutarch enriches the laconic myth corpus by reporting that the Lacedaemonians were content with replying to a letter with only the words "About what you wrote: no." Writing style is part of the message.

https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext...

Growing up bilingual, I personally always found Greek more verbose than English even in brevity. It's good for avoiding ambiguity and getting your intent across but sometimes bad for colloquial communication.

epilys commented on     · Posted by u/epilys
epilys · a year ago
First published in the Metropolitan Museum Journal, vol. 56, 2021, pp.160-73.

This study focuses on artist-designed frames at the end of the 19th century, many of which are preserved in the Havemeyer collection at the Metropolitan Museum, with a particular emphasis on a material known at the time as pâte coulante, unique in its ability to render extraordinary profiles, some of which could not have been realized by any other method available at the time. Although frames in pâte coulante can be seen surrounding the works of many late 19th century and early 20th century paintings, this study refers to the few superb examples available for study in the Metropolitan Museum and in private collections, which in many cases surround works by Edgar Degas. For artists like Degas, this method became crucial for executing radical frame designs. To reinforce the argument that the process of template-cut pâte coulante granted artists and framemakers the freedom to turn any design into a reliable and serviceable moulding, replicas of period mouldings were recreated using the available historic information, and the results gleaned from this technical study are included here.

u/epilys

KarmaCake day1093December 24, 2020
About
Virtualization and Emulation Engineer at Linaro, speaking on behalf of myself and not my employer

Maintainer of Rust subsystem on QEMU, and vhost-user devices on rust-vmm. Making a terminal e-mail client in my free time.

https://github.com/epilys https://pitsidianak.is/ manos@pitsidianak.is @epilys:matrix.org

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