Posts
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Following
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Followers
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A relatively new professional kernel hacker, born in August 6, 2000, and living in Korea (South!).

- Linux Kernel Developer @ Oracle (Linux Kernel MM) (2025.02 ~ Present)
- Reviewer for the Linux Slab subsystem
- Former Intern @ NVIDIA, SK Hynix, Panmnesia (Security, MM and CXL)
- B.Sc. in Computer Science & Engineering, Chungnam National University (Class of 2025)

Opinions are my own.

My interests are:
Memory Management,
Computer Architecture,
Circuit Design,
Virtualization
hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
In the ACPI specification; the character representing ACPI root namespace ('\') seems to be escaped (' and \') and looks like this.

How have people been reading this?
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @liskin@genserver.social
Edited 1 year ago
@liskin @cwayne @lkundrak whaaaat
am I being too conservative 🤣
asian countries tends to be conservative a little bit (although I am not at all - that's the problem)
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hyeyoo

Harry (Hyeonggon) Yoo

uni festival
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hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
my keyboard is not responding until the kerenel is loaded. what's wrong I want uefi please
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hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
UEFI (Unified Extensible Firmware Interface) standard defines the interface between platform firmware and OS (loader). UEFI only standards the interface with the firmware, but its implementation follows the Platform Integration (PI) standard, not UEFI. UEFI completely replaces BIOS used in traditional IBM PC environments.

An OS loader reads information such as ACPI tables, memory maps, etc. through UEFI and passes it to OS, which then takes over control. Most of the services provided by UEFI, including the ACPI Table and Memory Map, are not accessible after OS loader calls the UEFI's Boot Service ExitBootServices().

Intel provides open source reference implementations of firmware that adhere to the UEFI standard called EDK 2. The firmware also implements PCI host bus controllers, bus drivers, and device drivers.

In order to add CXL memory to the memory map during system initialization, the firmware must have CXL support added so that you can set up a CXL host bridge, switch, and device at system initialization before OS has taken the control.
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hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
In ACPI-compatible OS environment, NUMA node of memory ranges and distance matrix between NUMA nodes are parsed from ACPI SRAT/SLIT tables and they are provided firmware.

ACPI HMAT describes latency/bandwidth characteristics.

CDAT is a set of registers in CXL that reports bandwidth/latency characteristics of CXL devices/switches. it is consumed by firmware to produce HMAT/SRAT tables.
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @lkundrak@octodon.social
@lkundrak @ljs @vbabka I quite like it
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @ljs
@ljs that's a part of the reason why I don't like debating non-technical topics.
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hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
why does raid1 rebuild take longer than it should
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hyeyoo

Harry (Hyeonggon) Yoo

UEFI/ACPI is killimg my brain
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hyeyoo
repeated
AkaSci@fosstodon.org

AkaSci 🛰️

Edited 1 year ago

NASA is sending a software update to the Voyager 2 spacecraft today!

Data will be sent at 16 bps with a 19 kW transmitter using the 70-m dish at DSN Canberra.
Distance: 20 billion km
Light travel time: 18:40 hours

The patch contains logic to recover from glitches similar to the one in May 2022, when the AACS system on Voyager 1 was sending garbled data. The root cause was not diagnosed. The patch will be activated on Oct 28. Voyager 2 will be next.

https://www.jpl.nasa.gov/news/nasas-voyager-team-focuses-on-software-patch-thrusters

1/n

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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @liskin@genserver.social
@liskin @cwayne @lkundrak

do you remember what did you write? 😁
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @ljs
@ljs @cwayne @vbabka
belly can be reduced by your effort, at least ;)
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @ljs
@ljs @cwayne
You're welcome, mate!
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @ljs
@ljs @cwayne

but at the same time you need to hurry a bit (if you are planning),
my father had me in early 40s and he's 64 now
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @cwayne@hachyderm.io
@cwayne @ljs

Oh please I want to sleep 9-10 hours a day
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @cwayne@hachyderm.io
@cwayne @ljs
don't get what I've just read lol
guess both of you being sick in a different way
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @cwayne@hachyderm.io
@cwayne @ljs

oh I slept like this few months ago and it was terrible for your work quality
get better soon!
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hyeyoo

Harry (Hyeonggon) Yoo

Edited 1 year ago
https://coverage.kerneltesting.org/slab-experimental-6283c415/mm/

This is a merged LCOV output of my mm & slab test coverage from 30 different kernel configurations.

Looks mostly fine but there are a few small problems:
- Sometimes numbers are inconsistent
- Omission of (some) inline function coverage
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hyeyoo

Harry (Hyeonggon) Yoo

Reply to @hyeyoo
Edited 1 year ago
Found the cause: my SSD's throughput is 500MB/s, and when it's saturated, IO latency spikes up to several seconds.
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