UNIX/BSD and Linux Kernel
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Chris Wellons ☛ A more robust raw OpenBSD syscall demo
Ted Unangst published dude, where are your syscalls? on flak yesterday, with a neat demonstration of OpenBSD’s pinsyscall security feature, whereby only pre-registered addresses are allowed to make system calls. Whether it strengthens or weakens security is up for debate, but regardless it’s an interesting, low-level programming challenge. The original demo is fragile for multiple reasons, and requires manually locating and entering addresses for each build. In this article I show how to fix it. To prove that it’s robust, I ported an entire, real application to use raw system calls on OpenBSD.
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Koehntopp ☛ 50 years in filesystems: 1974
Progress is sometimes hard to see, especially when you have been part of it or otherwise lived through it. Often, it is easier to see if you compare modern educational material, and the problems discussed with older material. And then look for the research papers and sources that fueled the change.
In Linux (and Unix in general), this is easy.
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Koehntopp ☛ 50 years in filesystems: 1984
Progress is sometimes hard to see, especially when you have been part of it or otherwise lived through it. Often, it is easier to see if you compare modern educational material, and the problems discussed with older material. And then look for the research papers and sources that fueled the change.
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Graphics Stack
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Tony Garnock-Jones ☛ Linux DRM Dumb Buffers are slow to read, not write (eighty-twenty news)
Small experiments in the use of libliftoff to try out the modern Linux graphics stack drove home quite how slow DRM “dumb buffers” can be, but also that it’s reading that’s slow, not writing.
Reading from a “dumb buffer” on my AMD GPU is orders of magnitude slower than reading from RAM. It can take seconds to read out a full 4k frame. It’s roughly a thousand times slower than reading RAM.
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