RE: Updated 2.4 TODO List

From: Chris Swiedler (ceswiedler_lk@mindspring.com)
Date: Thu Oct 12 2000 - 10:02:50 EST


> On Wed, 11 Oct 2000 18:10:40 -0400,
> tytso@mit.edu wrote:
> >Are you sure it was compiled with the correct CPU? If you configure the
> >CPU incorrectly (686 when you only have a 586, etc.) the kernel *will*
> >refuse to boot.
> >
> >Maybe we should have the kernel print the CPU information it was
> >compiled with before it does anything else..... It'll make it easier to
> >catch what may be a fairly common set of PEBCAK case....
>
> Unfortunately any code like this
> if (a)
> b = 99;
> generates conditional move (cmove) instructions on 686. In vsprintf.c
> there are several of these constructs, in particular strnlen generates
> it. So printk("%s", text) tends to fault as well. Some people have
> argued that critical routines should always be compiled with -i386,
> unfortunately that includes all of printk and all console handling
> (both serial and screen), not really an option.
>
> If anything is going to detect the mismatch and complain, it has to be
> the boot loader, after uncompressing and before entering the kernel
> proper.

But the kernel should be able to write directly to the screen, even if it's
extremely minimal information. Something like how LILO does it: test the
common hang-on-boot conditions (like wrong CPU type) and print a single
character after each test.

chris

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