linux-kernel - Re: FP in kernelspace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 30 Jul 2006 17:40:10 +0300
From:	Avi Kivity <avi@...o.co.il>
To:	Jiri Slaby <jirislaby@...il.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: FP in kernelspace

Jiri Slaby wrote:
>
> Hello,
>
> I have a driver written for 2.4 + RT patches with FP support. I want 
> it to work
> in 2.6. How to implement FP? Has anybody developped some "protocol" 
> between KS
> and US yet? If not, could somebody point me, how to do it the best -- 
> with low
> latency.
> The device doesn't generate irqs *), I need to quickly respond to 
> timer call,
> because interval between two posts of data to the device has to be 
> equal as much
> as possible (BTW is there any way how to gain up to 5000Hz).
> I've one idea: have a thread with RT priority and wake the app in US 
> waiting in
> read of character device when timer ticks, post a struct with 2 floats 
> and
> operation and wait in write for the result. App computes, writes the 
> result, we
> are woken and can post it to the device. But I'm afraid it would be 
> tooo slow.
>
> *) I don't know how to persuade it (standard PLX chip with unknown 
> piece of
> logic behind) to generate, because official driver is closed and _very_
> expensive. Old (2.4) driver was implemented with RT thread and timer, 
> where FP
> is implemented within RT and computed directly in KS.
>
> So 2 questions are:
> 1) howto FP in kernel
>
kernel_fpu_begin();
c = d * 3.14;
kernel_fpu_end();

-- 
error compiling committee.c: too many arguments to function

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/