smxiAug 6, 2024
Malcom of #opensuse came up with interesting #inxi support question: in graphics devices, there are 4 PCI 03h subclasses: 300 vga compatible; 301 xga (no code for this in lunux kernel according to kernel thread); 302 3D controller (only seen so far on intel + nvidia Optimus laptops, seem to use intel gpu port for output); 380 other (AMD uses this class for igpu+dgpu systems, like APU + discrete gpu). But 380 is a catchall for anything not in first 3. I cannot think what to call these.
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Show threadsmxi

In a good #linux kernel thread it was suggested that only 300 is used for output, but it was also noted that vga itself is deprecated, making the default names of these display device types quite misleading, except xga, which apparently no longer exists. AMD to make matters worse gives the string "Display controller" to 380 subclass but 03h class is Display controller so that's not useful since it's redundant.

This is core reality of #inxi : finding out what things actually _are_ sigh...
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Aug 6, 2024 at 6:43pmWeb
Show threadsmxiAug 6, 2024
You would be amazed at how difficult it is to find someone saying nonambiguously what a technical thing actually _is_. I've started suspecting that tech is so chaotic under the covers that people don't actually know what the tools they rely on are. Like a carpenter saying a hammer is what he uses to hammer in nails. I find it almost impossible to get answers to such questions for #inxi unless I can find a relevant #linux kernel email or doc, or a random source who fully understood the tech.
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Show threadsmxiAug 6, 2024

https://lore.kernel.org/lkml/202306130[email protected]/

That's so far the only thread I could find that directly with this issue but its main concern is display controller subclass 0300 vga compatible detections.

Sometimes if I can find real kernel docs they help in #inxi research. Sometimes not.

This thread suggests vga itself is deprecated at which point one wonders if they will keep tossing stuff into the 380 other basket. Calling something vga is confusing for most users with only HDMI DVI DP physical ports.

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[PATCH v7 0/8] PCI/VGA: Introduce is_boot_device function callback to vga_client_register - Sui Jingfeng

Show threadsmxiAug 10, 2024

For anyone into #inxi / linux graphics arcana, ongoing updates.

https://docs.kernel.org/gpu/vga-switcheroo.html

As I suspected real data comes krom kernel docs. Unfortunately switcheroo state data lives in /sys/kernel/debug which is root read only. But helped define the problem. switcherooctl also has a tiny bit of info with list option but it only shows gpus available.

#mrmazda found great set of hardware, same boards, intel igpu. One with nvidia card. Gpu class id switched depending on w/wo dgpu! ID dynamic!

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VGA Switcheroo — The Linux Kernel documentation