Incorrectness for fun and profit

Incorrectness for fun and profit

[Rick Hohensee]

In 2.4 init/main.c we have...

 * Versions of gcc older than that listed below may actually compile
 * and link okay, but the end product can have subtle run time bugs.
 * To avoid associated bogus bug reports, we flatly refuse to compile
 * with a gcc that is known to be too old from the very beginning.
 */
#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 1)
#error Sorry, your GCC is too old. It builds incorrect kernels.
#endif

Note that I've elided the 9 from the minor version number. I also tweaked
the #define asmlinkage in whereveritis.h to look a bit more like 2.2, got
rid of the arch=bla switch to gcc, and built the kernel I'm using at the
moment with gcc 2.7.2.3. I'm looking for "subtle run time bugs". OK, I'm
desparate for entertainment. That's a given. Where should I look?
Everything I'm cognizant of so far is real pretty. I WANT BUGS! WHERE ARE
THE BUGS?

This is not a bogus bug report. This is a repeatable bug request.


Incorrectly yours,

Rick Hohensee
:; cLIeNUX0 /dev/tty12  12:43:36   /
:;get /Linux/version
Linux version 2.4.0-test10 (@cLIeNUX) (gcc version 2.7.2.3) #10 Thu Nov 9
03:11:45 2000
:; cLIeNUX0 /dev/tty12  13:03:02   /
:;




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Re: Incorrectness for fun and profit

[Keith Owens]

On Thu, 9 Nov 100 12:15:19 -0500 (EST), 
Rick Hohensee <humbubba@smarty.smart.net> wrote:
>built the [2.4] kernel I'm using at the
>moment with gcc 2.7.2.3. I'm looking for "subtle run time bugs". OK, I'm
>desparate for entertainment. That's a given. Where should I look?

2.4.0-test10 kernel/module.c

static struct module kernel_module =
{
	size_of_struct:		sizeof(struct module),
	name: 			"",
	uc:	 		{ATOMIC_INIT(1)},
	flags:			MOD_RUNNING,
	syms:			__start___ksymtab,
	ex_table_start:		__start___ex_table,	
	ex_table_end:		__stop___ex_table

gcc 2.7.2.3 miscompiles structures that have internal labeled structure
initializers.  uc gets misaligned, ex_table_start is then misaligned
and the exception table handling fails.

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