Re: [PATCH v12 00/21] Re-introduce h8300 architecture

[Yoshinori Sato]

At Mon, 11 May 2015 21:04:30 +0200,
Arnd Bergmann wrote:
> 
> On Monday 11 May 2015 10:50:27 Guenter Roeck wrote:
> > On Mon, May 11, 2015 at 03:26:19PM +0900, Yoshinori Sato wrote:
> > > Changes for v12
> > > - IRQ chip convert to OF
> > > - dts cleanup
> > > - some headers use generic
> > > - rebase to v4.1-rc3
> > > 
> > Configurations in arch/h8300/configs shtill build ok.
> > 
> > make allmodoconfig, after fixing the spi build error, results in
> > 
> > ERROR: "csum_partial_copy_nocheck" [net/ipv6/ipv6.ko] undefined!
> > ERROR: "ip_compute_csum" [net/ipv6/ip6_gre.ko] undefined!
> > ERROR: "ip_fast_csum" [net/ipv4/xfrm4_mode_beet.ko] undefined!
> > ERROR: "ip_compute_csum" [net/bridge/bridge.ko] undefined!
> > ERROR: "ip_fast_csum" [net/bridge/bridge.ko] undefined!
> > ERROR: "ip_fast_csum" [net/bridge/br_netfilter.ko] undefined!
> > ERROR: "ip_fast_csum" [net/atm/mpoa.ko] undefined!
> > ERROR: "__ucmpdi2" [fs/btrfs/btrfs.ko] undefined!
> > ERROR: "ip_compute_csum" [drivers/scsi/scsi_debug.ko] undefined!
> > ERROR: "ip_fast_csum" [drivers/net/slip/slhc.ko] undefined!
> > ERROR: "__ucmpdi2" [drivers/md/bcache/bcache.ko] undefined!
> > ERROR: "__ucmpdi2" [drivers/iio/imu/inv_mpu6050/inv-mpu6050.ko] undefined!
> > 
> > csum_partial_copy_nocheck, ip_compute_csum, and ip_fast_csum need to be exported
> > from arch/h8300/lib/checksum.c.
> 
> Interesting. From what I can see, the  arch/h8300/lib/checksum.c file
> contains a completely generic implementation of the IP checksum code.
> That should not be necessary at all, and is more likely to lead to
> subtle errors like the one you see here.
> 
> It would be better to do one of two things:
> 
> a) use the code from lib/checksum.c that is known to work well, and that
>    contains all the necessary exports. It seems that the h8300 is
>    almost an except copy of the generic code, it just misses a few
>    improvements that were done already in the kernel.
> 
> b) provide an optimized implementation written in assembly where necessary.
>    This can provide a significant performance improvement for TCP/IP
>    networking.

I think option a.
It was being written by an assembler before, so that was just left.

> > No idea what to do about the missing __ucmpdi2
> > symbol, or what causes it.
> 
> This is a libgcc symbol provided by arch/h8300/lib/ucmpdi2.c in patch
> 15. The other similar functions are written in assembly and exported
> from arch/h8300/kernel/h8300_ksyms.c, while this one is written in C
> and missing the export. It should be added in the file that defines
> the function.
>

Yes. Added for h8300_ksyms.c.

> 	Arnd

Thanks.

-- 
Yoshinori Sato
<ysato@xxxxxxxxxxxxxxxxxxxx>
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