3 ms·
Keep in mind that /dev/fb, on a modern system, isn't an actual framebuffer on your GPU. It's a land of make-believe, mostly supported to get the kernel console
by Jasper_ 9y ago
Keep in mind that /dev/fb, on a modern system, isn't an actual framebuffer on your GPU. It's a land of make-believe, mostly supported to get the kernel console ("fbcon") working. Going back for at least 10 years, the kernel mode-setting API (KMS) is used to display buffers, and there's compatibility code which sets up a user-space buffer in the KMS subsystem [0] which is swapped to when fbcon happens through a large chain of strange events that are hard to describe. This explains why you can't write to a /dev/fb during an active X11 session and have it show up: it's a fake buffer that only shows up when KMS isn't in use.
[0] https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/drm_fb_helper.c https://github.com/torvalds/linux/blob/master/drivers/gpu/dr...
- therein 9y agoThat is correct. One exception perhaps is embedded devices with displays, including EInk tablets. For instance one thing I have been working on is a library that allows writing to and partially refreshing an EInk display with low latency enabling this[0]. I am curious what would happen if I got xorg working on this and used an additional application to call the `refresh` ioctl so that the changes get displayed on the screen. [0] https://gfycat.com/CornyHugeIndianRhinoceros https://gfycat.com/CornyHugeIndianRhinoceros
- gandreani 9y agoThat's very awesome! What tablet and project is that?
- therein 9y agoThanks. It is the Remarkable Tablet but the API is entirely undocumented. Took a fair bit of analysis to get it to this state but now it is actually ready for people to build their own applications upon it. The GitHub project: https://www.github.com/canselcik/libremarkable https://www.github.com/canselcik/libremarkable
- gandreani 9y agoThank you very much! I will check out both very soon. I'm interested in a lightweight portable ssh terminal eink device and this combination might just work for me
- hultner 9y agoOh yes I've been looking for the same thing. Would like something I could connect a keyboard to and attach a tmux session. Would be a great work machine outside during summer time.
- tomcooks 9y agoWow!
- codetrotter 9y agoThis is cool, you should post it as a “Shown HN”. And don’t get discouraged if it doesn’t immediately garner attention. Post it again later if you only get an insignificant amount of upvotes. Your project is front page worthy and if it doesn’t get there the first time then it’s just bad timing / bad luck (or poorly worded title, that’s a possibility as well of course). Post it until it gets to the front page, waiting a couple of days or more between each time you post it.