From: dhylands@gmail.com (Dave Hylands)
To: kernelnewbies@lists.kernelnewbies.org
Subject: about 64-bits division in kernel
Date: Sat, 21 May 2011 00:22:14 -0700 [thread overview]
Message-ID: <BANLkTik_9taPLq5h2iCHmADioA5VJaF7ZQ@mail.gmail.com> (raw)
In-Reply-To: <BANLkTimx1rAjiKefMdyvVrTONgf4HWka0g@mail.gmail.com>
Hi miloody,
...snip...
> I found div64.h is located at includ/asm-generic/div64.h instead of
> include/linux/
> BTW, I still cannot figure out why kernel doesn't adopt the gcc's solution.
> libgcc.a will be compiled by different platform, arm, mips, etc.
> And that should be safe for kernel to adopt it.
I believe that the gcc approach is only safe from user-space, and may
cause traps from within kernel space.
>From the reading I've done, gcc expects a certain environment, and the
kernel provides a different environment.
I believe that the primary reason has to do with the fact that libgcc
also provides floating point support, which doesn't work in the
kernel, so they don't allow any of libgcc to be used. I believe that
there are people working on getting support for the integer stuff, but
I'm not sure what the status of this is.
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
prev parent reply other threads:[~2011-05-21 7:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-20 3:34 about 64-bits division in kernel loody
2011-05-20 4:15 ` Dave Hylands
2011-05-20 5:51 ` loody
2011-05-20 6:47 ` Dave Hylands
2011-05-21 6:57 ` loody
2011-05-21 7:22 ` Dave Hylands [this message]
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