Re: [PATCH] Move BUG/BUG_ON/WARN_ON to asm headers

From: Bartlomiej Zolnierkiewicz (
Date: Sat Jun 07 2003 - 10:43:15 EST

Hi Paul,

What about adding asm-generic/bug.h ?


On Sat, 7 Jun 2003, Paul Mackerras wrote:

> Linus, > > This patch moves the definitions of BUG, BUG_ON and WARN_ON from > <linux/kernel.h> to <asm/bug.h> (which <linux/kernel.h> includes), and > supplies a new implementation for PPC which uses a conditional trap > instruction for BUG_ON and WARN_ON, thus avoiding a conditional > branch. This patch trims over 50kB from the size of the kernel that I > use on powermacs. > > With this patch, on PPC we have a __bug_table section in the vmlinux > binary, and also in modules if they use BUG, BUG_ON or WARN_ON. The > __bug_table section has one entry for each BUG/BUG_ON/WARN_ON, giving > the address of the trap instruction and the corresponding line number, > filename and function name. This information is used in the exception > handler for the exception that the trap instruction produces. The > arch-specific module code handles the __bug_table section so that > BUG/BUG_ON/WARN_ON work correctly in modules. > > Several architecture maintainers have acked this change. It should be > completely benign for all of the other architectures (though they may > decide to do something similar if they have a conditional trap > instruction available). > > Please apply. > > Thanks, > Paul.

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