From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>
Subject: Re: [Xenomai-core] [Xenomai-commits] r4392 - /trunk/include/asm-x86/arith_64.h
Date: Sun, 16 Nov 2008 13:13:27 +0100 [thread overview]
Message-ID: <49200E67.3000000@domain.hid> (raw)
In-Reply-To: <491FF78D.9000609@domain.hid>
Jan Kiszka wrote:
> Gilles Chanteperdrix wrote:
>> Author: gch
>> Date: Sun Nov 16 03:30:40 2008
>> New Revision: 4392
>>
>> URL: http://svn.gna.org/viewcvs/xenomai?rev=4392&view=rev
>> Log:
>> Implement nodiv_ullimd on x86_64
>>
>> Modified:
>> trunk/include/asm-x86/arith_64.h
>
> Nice. This solves the user-triggerable kernel oops due to idiv overflows
> in the original version (rt_task_sleep_until(1LL<<63);). I happened to
> receive such a bug report on Friday and was about to consider
> alternative solutions beyond limit checks.
>
> But how accurate is this conversion? I mean how many bits can we lose
> when doing xnarch_ns_to_tsc(xnarch_tsc_to_ns(x))?
Thanks to a little addition, nodiv_ullimd has the same precision as ullimd.
>
> Final question: Already prepared a 32-bit version? :)
Yes, the generic vercion should work, provided we implement
__rthal_add96and64
which does an addl and two adcl
--
Gilles.
prev parent reply other threads:[~2008-11-16 12:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1L1XPO-0006Xh-1s@domain.hid>
2008-11-16 10:35 ` [Xenomai-core] [Xenomai-commits] r4392 - /trunk/include/asm-x86/arith_64.h Jan Kiszka
2008-11-16 12:13 ` Gilles Chanteperdrix [this message]
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