[PATCH][TRIVIAL] Remove bogus "value 0x37ffffff truncated to 0x37ffffff"warning.

[Bart Samwel]

Tim Cambrant wrote:
> On Sat, Jan 10, 2004 at 04:40:30PM +0100, Mario Vanoni wrote:
>
> > Compiling the kernel under 2.6.1-mm2, gcc-3.3.2
> > (same messages as under 2.6.1-rc1-mm1, re-tested),
> >
> > arch/i386/boot/setup.S: Assembler messages:
> > arch/i386/boot/setup.S:165: Warning: value 0x37ffffff truncated to 
> > 0x37ffffff
>
> This is apparently a known problem and has existed for a long time,
> but no-one has fixed it for some reason. I asked the exacly same
> question a few months ago, and someone told me that this issue has
> been around forever, but is noticed under 2.6, since it is less
> verbose during the compilation. I'll pass the message that was told
> to me: If you've got a fix, it would surely be included in the kernel.

The problem is in the MAXMEM macro. This macro takes the inverse of a 
positive number, subtracts another number, and the negative result 
overflows the negative range of a 32-bit integer. The assembler 
truncates it, but apparently it can't print overly negative numbers 
correctly, that's why it looks so strange.

My proposed fix is attached: change the macro to subtract the numbers 
from 0xFFFFFFFF, and then add 1 at the end. That yields the same result, 
but without going through a negative intermediate value that needs to be 
truncated.

-- Bart



--- page.h.orig	2004-01-10 18:15:17.000000000 +0100
+++ page.h	2004-01-10 18:15:47.000000000 +0100
@@ -123,7 +123,7 @@

 #define PAGE_OFFSET		((unsigned long)__PAGE_OFFSET)
 #define VMALLOC_RESERVE		((unsigned long)__VMALLOC_RESERVE)
-#define MAXMEM			(-__PAGE_OFFSET-__VMALLOC_RESERVE)
+#define MAXMEM			(0xFFFFFFFF-__PAGE_OFFSET-__VMALLOC_RESERVE+1)
 #define __pa(x)			((unsigned long)(x)-PAGE_OFFSET)
 #define __va(x)			((void *)((unsigned long)(x)+PAGE_OFFSET))
 #define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)


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