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Comment by przmk | Hacker News Reader

I would venture to say that there is little overlap between X11 users and people with high-DPI screens.

We are under an article which tells you that you can have problems with Wayland and hiDPI screens. And for example I’m one of those people, who uses X11, because Wayland failed on many levels, like buggy video playing, crashing while changing monitors, or simply waking up my laptop with an external monitor, and I didn’t give more than a few days to fix these (cheers to the author to try this long), so I went back to X11. Which is still buggy, but on a “you can live with it level” buggy.

Btw, everybody who I know, and I too, changes the font size, and leaving the DPI scaling on 100%, or maybe 200% on X11.

> Btw, everybody who I know, and I too, changes the font size, and leaving the DPI scaling on 100%, or maybe 200% on X11.

Doesn't work if your screens are too different (e.g. 4k laptop screen and 32" desktop monitor).

You can scale down from a higher resolution to make the UI perceptively the same size. You can do this with xrandr --scale OR for example the GUI in Cinnamon on Mint after you check "fractional scaling" under X mind you.

It does work for Qt and KDE at least.

I have a setup with a high DPI monitor mixed with a normal DPI monitor and KDE over Wayland just works fine. The only issue that I found are with Libre Office doing weird over scaling and Chrome/Chromium window resizing his window to the oblivion.

I’ve been using X11 with high-DPI screens since 2013, but with integer scaling (200% or 300%), never fractional scaling.

Nobody's going to buy monitors where they need fractional scaling or multiple monitors with mixed DPI if they know it's broken.

Everyone’s so excited about the wave if windows users coming to Linux. Those people already have monitors.

I switched in 2018 and was surprised I couldn’t use fractional scaling on one monitor like I’d been doing for years on windows.

Not to mention that fractional scaling is practically required in order to use the majority of higher DPI monitors on the market today. Manufacturers have settled on 4K at 27" or 32" as the new standard, which lends itself to running at around 150% scale, so to avoid fractional scaling you either need to give up on high DPI or pay at least twice as much for a niche 5K monitor which only does 60hz.

Fractional scaling is a really bad solution. The correct way to fix this is to have the dpi aware applications and toolkits. This does in fact work and I have ran xfce under xorg for years now on hi-dpi screens just by setting a custom dpi and using a hi-dpi aware theme. When the goal is to have perfect output why do people suddenly want to jump to stretching images?

The overwhelming majority of the low-DPI external displays at this point are 24-27 1080p

Most high-DPI displays are simply the same thing with exactly twice the density.

We settled on putting exactly twice as many pixels in the same panels because it facilitates integer scaling

That doesn't gel with my experience, 1080p was the de-facto resolution for 24" monitors but 27" monitors were nearly always 1440p, and switching from 27" 1440p to 27" 4K requires a fractional 150% scale to maintain the same effective area.

To maintain a clean 200% scale you need a 27" 5K panel instead, which do exist but are vastly more expensive than 4K ones and perform worse in aspects other than pixel density, so they're not very popular.

Why not give up on high DPI?

Save money on the monitor, save money on the gpu (because it's pushing fewer pixels, you don't need as much oomph), save frustration with software.

4K monitors aren't a significant expense at this point, and text rendering is a lot nicer at 150% scale. The GPU load can be a concern if you're gaming but most newer games have upscalers which decouple the render resolution from the display resolution anyway.

I used to be like this. I actually ran a 14" FHD laptop with a 24" 4k monitor, both at 100%. Using i3 and not caring about most interface chrome was great, it was enough for me to zoom the text on the 4k one. But then we got 27" 5k screens at work, and that had me move to wayland since 100% on that was ridiculously small.

Why not 200% and increase font size slightly in all 3 cases?

Because although I don't care much about the chrome, I sometimes have to use it. For example, the address bar in firefox is ridiculously small. Also, some apps, like firefox (again) have a weird adaptation of the scroll to the zoom. So if you zoom at 300%, it will scroll by a lot at a time, whereas 200% is still usable.

Also, 200% on an FHD 14" laptop means 960x540 px equivalent. That's too big to the point of rendering the laptop unusable. Also, X11 doesn't support switching DPI on the fly AFAIK, and I don't want to restart my session whenever I plug or unplug the external monitor, which happens multiple times a day when I'm at the office.

14 fhd is 157 ppi 24 4k is 184 ppi

This really isn't this far off. If we imagined the screens overlayed semi-transparently an 16 pixel letter would be over a 14 pixel one.

If one imagines an ideal font size for a given user's preference for physical height of letterform one one could imagine a idealized size of 12 on another and 14 on the other and setting it to 13 and being extremely close to ideal.

>So if you zoom at 300%, it will scroll by a lot at a time, whereas 200% is still usable.

This is because it's scrolling a fixed number of lines which occupy more space at 300% zoom notably this applies pretty much only to people running high DPI screens at 100% because if one zoomed to 300% otherwise the letter T would be the size of the last joint on your thumb and legally blind folks could read it. It doesn't apply to setting the scale factor to 200% nor the setting for Firefox's internal scale factor which is independent from the desktop supports fractional scaling in 0.05 steps and can be configured in about:config

layout.css.devPixelsPerPx

Right, and 27" 5k is 218 ppi, which isn't that much more than the 24". But don't forget that viewing distance plays a big role in this, and my 14" laptop is much closer than a 27" monitor. Bonus points for our specific model having an absolutely ridiculous viewing angle, so if it's too close the outer border are noticeably dark.

Why to have a home if you can sleep in a cardboard box?

That's a really odd thing to say.

I don't really care about this but here's an example:

I have 2 27" screens, usually connected to a windows box, but while working they're connected to a MBP.

Before the MBP they were connected to several ThinkPads where I don't remember what screen size or scaling, I don't even remember if I used X11 or Wayland. But the next ThinkPad that will be connected will probably be HiDPI and with Wayland. What will happen without buying a monitor? No one knows.

There is no particular reason for this theory to be true. X supports high DPI screens well and has for ages.

Fractional scaling is very common with high dpi screens. I don't I'd be able to have a 175% scaling on my 14" 3k screen with X11.

Maybe it supports it sure, the problem is that it doesn't work at all.

It does work and has worked for over a decade. You can configure scaling under settings in Cinnamon or plasma for instance or via environmental variables in a simple environment like i3wm.

The post is from the Dev of i3wm an x11 window manager complaining among other things about how well his 8k monitor works under x11 and how poorly it works under Wayland.

You can also consult the arch wiki article on high DPI which is broadly applicable beyond arch

Yes, I know all that. Except it doesn't work. At all.

Ten years ago there were cursor clipping issues, cursor coordinates issues and crashes and I've been home-baking patches for that.

Also it was impossible for one X session to span across two GPUs. Dunno if that was improved.

Now it's bit better, but for sure your amdgpu will entertain you with little nice crashes when you run something heavy on a scaled display.

I'm not even talking about VRR, HDR and all that stuff.

In that time I've had Hidpi work perfectly on first on Nvidia then recently on AMD GPUs on several different distros and desktops all running on X on several distros. They all worked out of the box and were able to scale correctly once configured.

The totality of my education on the topic was reading the arch wiki on hidpi once.

AFAIK one cannot span one x session across multiple GPUs although AMD had something that it once referred to as "eyefinity" for achieving this.

It is rarely needed discreet GPU often support 3 or even 4 outputs

One may wonder if you tried this a very long time ago back when AMD sucked and Nvidia worked well in 2005-2015

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