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Z8086: Rebuilding the 8086 from Original Microcode

https://nand2mario.github.io/posts/2025/z8086/

#HackerNews #Z8086 #Rebuilding #8086 #Microcode #RetroComputing #Technology #Innovation

If you use #btrfs on kernels ranging from 6.12 to 6.19 and get the error:

VFS: Unable to mount root fs on unknown_block(0,0)

Add the 'btrfs' and 'microcode' hooks to /etc/mkinitcpio.conf via chroot and rerun initramfs generation.

If that doesn't help install `intel-ucode.img` and add it to your grub boot parameters in the initrd list.

If that still doesn't help (happens on Intel 3770k and older) disable #zstd initramfs compression, use gzip instead.

You are welcome

#initramfs #microcode

@adingbatponder yes as in the #remite part of it is offline so no #AMT functionality.

But the general #microcode is still there.

This is called a "#neutered #ManagmentEngine" and "permanently disable" is also an option on commercial #UEFI|s like #ThinkPad.

Personally I want #LinuxBoot instead of UEFI!

Courtesy of Eric Rechlin of hpcalc.org, now you can watch a fat ugly guy who says "um" far too often, at HHC 2025 talking about and demonstrating the forthcoming Nonpareil II microcode-level simulation of various HP RPN calculators (currently HP-15C and HP-16C):

https://www.youtube.com/watch?v=eraikEonaJQ

The audience really liked that the graphics is fully scalable, rather than only having integer multiple scaling of a bitmap, in the original Nonpareil.

#hhc2025 #Nonpareil2 #rpn #calculator #microcode

At HHC 2025, I learned of the existence of another HP-95C in private hands, which makes four that I know of.

The HP-95C was a desktop scientific programmable printing calculator, with continuous (CMOS) memory but no card reader. It would have been introduced in 1976, positioned between the HP-91 desktop non-programmable printing scientific, and the HP-97 desktop programmable printing scientific with magnetic card reader.
1/
#hhc2025 #rpn #calculator #microcode #simulator

I just gave an HHC 2025 presentation and demonstration of Nonpareil II, my work--in-progress microcode-level HP calculator simulator, now written in C++20 using the Qt6 toolkit. Compared to the original, it uses vector graphics for smooth scaling over a wide range of window sizes.
#hhc2025 #rpn #calculator #microcode #simulator

World's first #CPU-level #ransomware can "bypass every freaking traditional technology we have out there" — new #firmware-based attacks could usher in new era of unavoidable ransomware
Beek, #Rapid7's senior director of threat analytics, revealed AMD Zen chip bug gave him idea that highly skilled attacker could in theory "allow those intruders to load unapproved #microcode into the processors, breaking encryption at the hardware level and modifying CPU behavior at will."
https://www.tomshardware.com/pc-components/cpus/worlds-first-cpu-level-ransomware-can-bypass-every-freaking-traditional-technology-we-have-out-there-new-firmware-based-attacks-could-usher-in-new-era-of-unavoidable-ransomware

https://www.theregister.com/2025/05/11/cpu_ransomware_rapid7/

Spoiler alert: Beek followed through and wrote proof-of-concept code for #ransomware that hides in the computer's #processor. "Of course, we won't release that, but it's fascinating, right?"

This, according to Beek, is the worst-case scenario. "Ransomware at the #CPU level, #microcode alteration, and if you are in the CPU or the #firmware, you will bypass every freaking traditional [anti-malware] technology we have out there."

Von #AMD-Lücke inspiriert:

#Forscher warnt vor #Ransomware im #CPU-Microcode

Eine Lücke in #AMD-CPUs ermöglicht manipulative Eingriffe in den #Microcode. Darin eingeschleuste #Ransomware wäre äußerst schwer zu bezwingen.

Eine #Ransomware-Infektion kann für Unternehmen weitreichende Folgen haben, die nicht selten auch in einer Insolvenz münden. Durch geeignete Maßnahmen lassen sich die Risiken für solche #Sicherheitsvorfälle eindämmen.

https://www.golem.de/news/von-amd-luecke-inspiriert-forscher-warnt-vor-ransomware-im-cpu-microcode-2505-196112.html

Linux 6.16 will warn users about outdated Intel microcode

Intel is routinely releasing new microcode for their processors to improve the processor’s performance and to fix critical issues, especially when dealing with security vulnerabilities that may be found in old microcode versions. This is to ensure that your system becomes more secure than before by eliminating security vulnerabilities.

A patch has been queued to the Linux kernel tip repository that will make its way to the Linux 6.16 kernel. It warns the user on boot that the microcode version for the processor is old and that it needs to be updated to ensure security. Userspace applications can determine whether your computer is using the old microcode via the /sys/devices/system/cpu/vulnerabilities/old_microcode file.

The kernel, if running in the old microcode, will be tainted with the TAINT_CPU_OUT_OF_SPEC flag, making it more difficult for kernel bugs that have to do with the old microcode to be reported directly to the bug tracker. The implementation relies on a manually-maintained list of processors found in the intel-ucode-defs.h file. It contains a list of structures that contain the following variables:

flags: List of flags (always X86_CPU_ID_FLAG_ENTRY_VALID)
vendor: Processor vendor (always X86_VENDOR_INTEL)
family: Processor family (usually 0x6 or 0xf)
model: Processor model
steppings: Processor stepping
driver_data: Processor microcode ID as an integer

Not only that, but all processors that are running on a debug microcode (that is, microcode ID with the 31st bit set to 1) are considered to be old.

We advise you to update your processor’s microcode to the latest version to ensure that there are no security vulnerabilities present.

#intel #Kernel #Linux #LinuxKernel #Microcode #news #processor #processors #Tech #Technology #update

🤡 Ah yes, because rewriting #microcode to run #RISC-V on #AMD #CPUs is *definitely* something everyone has on their weekend to-do list. 🛠️ What's next, trying to make a toaster run Crysis? 💡
https://rvspoc.org/en/S2502/ #weekendprojects #techhumor #toastergaming #HackerNews #ngated

Run RISC-V Binaries on AMD Zen-Series CPUs via Microcode Modification

https://rvspoc.org/en/S2502/

#HackerNews #RISC-V #AMD #Microcode #Zen-Series #Binaries #Technology

@nixCraft

#NixOS is interesting. Pretty reliable (not as much as #AtomicDesktops in my noob tests) while also performant

Note that such old hardware will have #microcode vulnerabilities and locking it down will further slow it down. At least thinking of #spectre or #meltdown (not sure if hyperthreading was even thought of back then)

Undocumented 8086 instructions, explained by the microcode

https://www.righto.com/2023/07/undocumented-8086-instructions.html

#HackerNews #Undocumented #8086 #instructions #microcode #technology #computing #retro #programming

Notes on the Pentium's Microcode Circuitry

https://www.righto.com/2025/03/pentium-microcde-rom-circuitry.html

#HackerNews #Pentium #Microcode #Microelectronics #ComputerArchitecture #TechHistory

Extensive Analysis of the Raptor Lake CPU Bug

Intel’s Raptor Lake CPUs, which form part of the 13th and 14th generation Intel Core desktop processor line, were celebrated for their hybrid architecture combining high-performance cores with efficiency cores. However, shortly after their release, a critical bug emerged that has led to system instability and, in some cases, permanent degradation of the affected chips.

#CPU #Bug #Microcode #Intel #Computer

AMD CPU microcode 的簽名漏洞在 Lobsters 上看到 Google 對上個月 AMD CPU 的 microcode 耕更新漏洞的分析：「Zen and the Art of Microcode Hacking」，看完後發現原來是自己設計出來的簽名驗證導致的... CPU 透過修正 microcode 修正問題算是行之有年的方法，可以在開機後讀進來改變本來設計的行為，也因為這個動作很危險，通常會加上數位簽名的方式確保只有原廠可以改。 AMD 在這邊的設計是用了 RSA 2048 bit 簽名保護，但把整把 RSA public key 放進去驗證會吃太多電晶體，所以這邊只存了 128-bit value 以節省電晶體空間，這邊本來以為是用 MD5 被撞，或是用… https://blog.gslin.org/archives/2025/03/06/12295/amd-cpu-microcode-%e7%9a%84%e7%b0%bd%e5%90%8d%e6%bc%8f%e6%b4%9e/ #algorithm #amd #cmac #cpu #hardware #key #microcode #number #random #rsa #security #vulnerability