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94- Intern @ NVIDIA Korea (Security System Software) (2024.06 ~)
- Ex-Intern @ Panmneisa (CXL emulation stuff) (~2023.12)
- Undergraduate majoring CSE (estimated graduation: Feb. 2025)
- Working as reviewer at Linux Slab subsystem
- Born in August 6, 2000
Opinions are my own.
My interests are:
Memory Management,
Computer Architecture,
Circuit Design,
Virtualization
looks like to hate something first and then find (wrong) reason to explain it
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would he/she help them if they go to church :(
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Hyeonggon Yoo
hyeyooCandidates:
- LTP
- KUnit
- kselftests
btw it is funny that the entire LTP suite gets killed every time it runs oom testcases. and LTP takes quite long time for a lightweight testing.
hmm... maybe run only a smaller subset of them?
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it won't land on the mainline ;)
(the consensus seems to be not using static calls in __exit)
but was fun!
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Hyeonggon Yoo
hyeyooCXL memory can be mapped as 'System RAM' or 'Soft Reserved' by platform firmware. Or it can be dynamically provisioned by (since v6.3) CXL region driver.
And 'Soft Reserved' or dynamically provisioned CXL RAM region can be used in two ways:
1. Applications mmap() to /dev/daxX.Y files, just like traditional persistent memory devices.
2. Kernel use it as System RAM via dax_kmem driver.
And a weird fact is that when dax_kmem onlines CXL (and other performance-differentiated like pmem) memory, to ZONE_NORMAL, not ZONE_MOVABLE.
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HAMMER SMASHED FILESYSTEM 🇺🇦
lkundrak@octodon.social
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Vlastimil Babka
vbabkaSo far...
26 files changed, 39 insertions(+), 4375 deletions(-)
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Hyeonggon Yoo
hyeyooI was hit by BUG_ON() because I enabled CONFIG_DEBUG_VIRTUAL=y.
It made my machine crash and I wrote and sent a quick hack to fix this.
https://lore.kernel.org/lkml/CAB=+i9QiJ=BXkQuCFJTh3dMXrkKQvVA2EM51Mj6SsDMimWQ71g@mail.gmail.com
Today I learned:
- Better to use proper tags for regzbot next time I report something, don't make @kernellogger do that instead of me.
- __init and __exit are compiler attributes that makes functions to be in specific ELF sections (.init.text and .exit.text), to drop portions of unused kernel code.
- When a kernel feature is built into kernel rather than built as a module, functions marked __init are dropped after initialization and functions marked __exit are dropped and never used. because you can't unload a built-in kernel feature ;)
- Some architectures drop .exit.text section at link time, but some drop at runtime. this is due to complexity of link-time reference counting between functions (? which I have no idea yet)
- On architectures that drop it at runtime, functions marked __exit are dropped in free_initmem() because .exit.text section is between __init_begin and __init_end.
- I need an automatic bisection system to save time in the future.
One piece of information I'm missing here is why it did not crash before the commit :(
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Thorsten Leemhuis (acct. 1/4)
kernellogger@fosstodon.org2/…patches from new or rare contributors should have some kind of tag to indicate things like
(1) I have no interest in learning how to do things better, I just want it fixed; I'm thus happy if someone dramatically changes the patch or writes a better one.
(2) I'd really like to learn how to do this properly, hence would be grateful if someone could guide me somewhat.
Why? Well, misunderstandings here can be annoying and a waste of time for both sides (and lead to situations like the above).
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Thorsten Leemhuis (acct. 1/4)
kernellogger@fosstodon.org"[…] Instead of accepting my [#LinuxKernel] patch or guiding me towards a better solution, he went ahead and implemented his own fix, giving me credit only for reporting the issue […]
My first contribution to the [#Linux] #kernel was a really frustrating and discouraging experience, dealing with people who do not think it’s important to get proper recognition for your work. […]"
https://ariel-miculas.github.io/How-I-got-robbed-of-my-first-kernel-contribution/
1/ Side note: I sometimes wonder if…
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