x86: Do not write to VGA memory space if CONFIG_VGA_CONSOLE is undefined
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From: H. Peter Anvin on 20 Apr 2010 00:10 On 04/19/2010 07:21 PM, Guenter Roeck wrote: > On Mon, Apr 19, 2010 at 05:02:25PM -0400, H. Peter Anvin wrote: >> Hi Guenter, >> >> I wanted to check where we are at... at the very least we should drop >> messages issued before initialization when isVGA != 1. >> >> Since serial ports require initialization, I really don't want to send >> messages to the serial port before the port has been initialized, but >> obviously it would be good to initialize earlyprintk as early as at all >> possible. >> > Moving setup_early_printk() around may be possible, but I do not know > the code good enough to take that risk. Even trying was a bad idea. > > I could submit a patch to add some protection into early_printk(), > to ensure it does not write into VGA memory space if there is no VGA, > and do that without changing current semantics - specifically, still > write into VGA memory space even if setup_early_printk() was not called > yet, but if boot_params.screen_info.orig_video_isVGA is set. > > I thought you indicated that you are opposed to changing the code, > and it looks kind of clumsy, so I concluded that it was not worth > trying again. Maybe I misunderstood - let me know. > > Guenter I think writing into VGA memory if we know there is a VGA device is there. I don't want to write to an uninitialized serial port, because that can cause all kinds of problems. But yes, dropping output to VGA if there isn't one makes a lot of sense. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |