I have hard time understanding why do they have to have a supervisor there to begin with
Linux Kernel Fastboot [pdf]
71–80 of 121 posts
Re: Linux Kernel Fastboot [pdf]
#72Do I understand correctly that the motivation for this is that the rear-view camera on the Chery Exeed LX runs Linux? Is it a good idea to ship a car with safety components running Linux?
As opposed to running what?
Linux (as in, the kernel) is extremely stable and well tested.
If the components in question utilise any significant features of the kernel, I strongly doubt some homegrown kernel-esque project will achieve more stability and reliability than Linux.
Sure, if it can be done with a (minimal) amount of embedded code then it quite possibly should be, but if a whole kernel is actually needed then Linux is a fine choice.
Re: Linux Kernel Fastboot [pdf]
#73Do I understand correctly that the motivation for this is that the rear-view camera on the Chery Exeed LX runs Linux? Is it a good idea to ship a car with safety components running Linux?
A huge percent of cars are already using Linux on their head units. The ones showing the backup camera.
E.g. new Mazdas have a Linux distro with DBus communicating between binaries and Opera browser to show UI. The actual UI is written in JavaScript and HTML.
Re: Linux Kernel Fastboot [pdf]
#74Do I understand correctly that the motivation for this is that the rear-view camera on the Chery Exeed LX runs Linux? Is it a good idea to ship a car with safety components running Linux?
Better to use a proprietary OS?
Re: Linux Kernel Fastboot [pdf]
#75Do I understand correctly that the motivation for this is that the rear-view camera on the Chery Exeed LX runs Linux? Is it a good idea to ship a car with safety components running Linux?
As opposed to running what? Linux (as in, the kernel) is extremely stable and well tested. If the components in question utilise any significant features of the kernel, I strongly doubt some homegrown kernel-esque project will achieve more stability and reliability than Linux. Sure, if it can be done with a (minimal) amount of embedded code then it quite possibly should be, but if a whole kernel is actually needed th…
QNX is still fairly popular in cars. Sometimes also QNX for the more critical things and Linux for the rest.
Re: Linux Kernel Fastboot [pdf]
#76How nostalgic! Mind you, I say that in a good way! This brings me back to the heydays of Sun Microsystems where they controlled both the hardware (SPARC) and the operating system (Solaris). Sun didn't hesitate to use this to their advantage. With Clear Linux, I see Intel doing some very similar things. Yes, this was just a story about boot time, but it led me to take a look at Clear Linux and it looks like it could b…
> Anyone have some experiences with this distro (for better or worse) that they'd like to share? Not much of one, but for a while I was playing with multiple distros trying to find the best possible power management for my laptop. (XPS 13 9380.) Clear did better than the Ubuntu installation that came with it -- but a dead octopus would have done better than that . It was sitting at 6W for non-CPU-intensive work, and…
The XPS 13 9380 is available with Linux pre-installed, why would you want to mess with that? Or was it a fun/hobby thing?
Re: Linux Kernel Fastboot [pdf]
#77Earlier quoted context omitted.
If you want just the important parts faulted in, you need to get the important parts into their own pages, preferably in order. I don’t know whether profile-guided linking is a thing.
PGO detects hot/cold functions and places them together¹ ², but I imagine whatever it needs on startup is probably not especially hot. …Though it might all be cold, which would have the same effect, actually. ― ¹ At least on GCC but I would be very surprised if clang doesn't also do this. ² You can also do this manually with __attribute__((hot)) and __attribute__((cold))
PGO may not be the right tool for this. Mozilla used custom instrumentation and linker scripts to achieve symbol ordering optimized for startup.
https://web.archive.org/web/20100223202038/http://blog.mozil...
Re: Linux Kernel Fastboot [pdf]
#78Earlier quoted context omitted.
> Just remove the sleep(2700). Such high quality discussion too!
> SATA driver init takes 100 to 200 ms even without a real disk While it’s a joke, they’re not particularly far from the truth, as noted in a different comment here. They do indeed wait for some parts to respond.
Would it be possible on multithreaded architectures to have a thread listening for the response, then setting a flag in /proc or somewhere else to indicate that the part is now active? That way, init code that does not depend on that device can continue to run.
Re: Linux Kernel Fastboot [pdf]
#79How nostalgic! Mind you, I say that in a good way! This brings me back to the heydays of Sun Microsystems where they controlled both the hardware (SPARC) and the operating system (Solaris). Sun didn't hesitate to use this to their advantage. With Clear Linux, I see Intel doing some very similar things. Yes, this was just a story about boot time, but it led me to take a look at Clear Linux and it looks like it could b…
I found it weird at first that you had to explicitly state Sparc and Solaris, but I guess we’re now at the point we’re a lot of users here weren’t around during Sun’s shine
Re: Linux Kernel Fastboot [pdf]
#80I'd really like to get my raspberry pi booting in a couple seconds. I have a few ideas for things I'd like to try but the boot time is too long. Don't need X11 but I would like to use raspbian.
If you do not need the graphical stack, there is room for optimization both in kernel and user space. On a similar board (4 ARM cores) with Ubuntu I managed to start user space applications in <2 seconds (from power on) and the complete boot (including Xorg/MATE) in <10 seconds. If you are interested, on Medium I have some write-up (same username, last post).
A link to said write-up: https://medium.com/@fmntf/adapting-ubuntu-for-the-automotive...