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. > even better if it could be used by the kernel decompression code), but > I suspect this is more involved than good old UART as you need to > manage fonts, pixel format, screen geometry, etc. > > OTOH it would be very useful for some retail devices that come without > an accessible serial line, but have a framebuffer set up by the > bootloader. > > Alex. -- 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
