Re: Another problem with compiling Linux kernel

[David Daney <ddaney@avtrex.com>]

Jonathan Day wrote:
> Hi again,
> 
> Using GCC 4.0.0 on the Broadcom SB1 MIPS64 board, the
> compilation crashes at the final link phase with the
> following errors:
> 
.
.
> `.exit.text' referenced in section `.pdr.20' of
> net/built-in.o: defined in discarded section
> `.exit.text' of net/built-in.o
> 

I know nothing about this one.

> My first thought was "ah, might be because I'm using
> an old GCC, so I'll try something more recent and see
> what happens". When trying GCC 4.1.0 (snapshot from
> 20051017), I get the following error:
> 
> In file included from include/linux/nfs_fs.h:15,
>                  from init/do_mounts.c:12:
> include/linux/pagemap.h: In function
> 'fault_in_pages_readable':
> include/linux/pagemap.h:237: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:237: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:237: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:237: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:243: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:243: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:243: error: read-only variable
> '__gu_val' used as 'asm' output
> include/linux/pagemap.h:243: error: read-only variable
> '__gu_val' used as 'asm' output
> make[1]: *** [init/do_mounts.o] Error 1
> make: *** [init] Error 2
> 
> This one may be a compiler bug (experimental GCCs are,
> well, experimental!) but it makes it somewhat harder
> to know if the later issue is resolved by using a
> different toolchain.
> 

This is not a GCC bug, but a change in GCC behavior.  One patch was 
posted here:

http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=Pine.LNX.4.61.0511022057140.3511%40trantor.stuart.netsweng.com

I don't know if the change made it into the linux-mips git repository or 
not.