On Thu, Aug 28, 2014 at 10:05 PM, Alexandre Courbot <gnurou@xxxxxxxxx> wrote: > On Thu, Aug 28, 2014 at 7:00 PM, jonsmirl@xxxxxxxxx <jonsmirl@xxxxxxxxx> wrote: >> On Thu, Aug 28, 2014 at 9:54 PM, Alexandre Courbot <gnurou@xxxxxxxxx> wrote: >>> On Thu, Aug 28, 2014 at 6:40 PM, jonsmirl@xxxxxxxxx <jonsmirl@xxxxxxxxx> wrote: >>>> On Thu, Aug 28, 2014 at 9:36 PM, Alexandre Courbot <gnurou@xxxxxxxxx> wrote: >>>>> On Thu, Aug 28, 2014 at 12:19 PM, jonsmirl@xxxxxxxxx <jonsmirl@xxxxxxxxx> wrote: >>>>>> Is there some existing way to do early printk type output to a >>>>>> framebuffer that has been set up by the bootloader? early printk is >>>>>> before any device drivers are loaded. >>>>>> >>>>>> If not, what would it take to create a way to do this? Something along >>>>>> the lines of build in the fbdev library and give it an address plus >>>>>> x/y layout of the buffer. Assume that everything else is set up and >>>>>> anything written to the buffer will appear on the display. Then hook >>>>>> into where the kernel does early printk on uarts and add in support >>>>>> for this buffer. The core fbdev library implements scrolling and >>>>>> graphical characters. >>>>> >>>>> simplefb does something like this (implement a console on top of a >>>>> framebuffer set up by the bootloader), but I don't think you can use >>>>> it for earlyprintk. It would be a very interesting option though (and >>>> >>>> simplefb is a device driver so it doesn't process the early output. >>>> This would need to be some custom code that gets the framebuffer >>>> address and x/y setup very early in the boot process. I'm fairly sure >>>> nothing like it current exists. >>> >>> You're right AFAICT. And although simplefb shares part of of idea it >>> also doesn't operate at the required level. Also contrary to what I >>> said it also does not implement a console, but just a framebuffer >>> device on top of which you need some more logic before you can think >>> about displaying strings. >> >> turn on fbconsole support and it should work. > > Yeah, but my point was, that I don't think you can use fbconsole that > early in the kernel? You can't. But all of the needed code is sitting there in fbconsole. There is just a small bit missing to make an early console work. Mainly just the bit about address of buffer and x/y layout. -- Jon Smirl jonsmirl@xxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
