From: Charles Forsyth <charles.forsyth@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] sysrfork fp bug?
Date: Mon, 21 Nov 2011 07:33:26 -0800 [thread overview]
Message-ID: <CAOw7k5hcpmt26NppfrFENPWS9_g6jD=XMhQzVMeS1usGQrwL0w@mail.gmail.com> (raw)
In-Reply-To: <93653898c4ceb27355b5fa1e548176aa@brasstown.quanstro.net>
registers are dead on entry to a function, so there's no point in saving
particular values, because they won't be used. on an amd64, however,
the kernel should
reset the FP-used flag, to cause the preset values to be set in the high FP
registers if the fork'd process does touch the FP.
On 21 November 2011 07:08, erik quanstrom <quanstro@quanstro.net> wrote:
> sysrfork() does *not* do a procsave before forking. thus the
> floating point registers in the new process are just going to
> be a copy of whatever was last saved, and perhaps nothing.
next prev parent reply other threads:[~2011-11-21 15:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-21 15:08 erik quanstrom
2011-11-21 15:33 ` Charles Forsyth [this message]
[not found] ` <CAOw7k5hcpmt26NppfrFENPWS9_g6jD=XMhQzVMeS1usGQrwL0w@mail.gmail.c>
2011-11-21 15:43 ` erik quanstrom
2011-11-21 23:01 ` erik quanstrom
2011-11-21 15:48 ` erik quanstrom
2011-11-21 22:08 ` erik quanstrom
2011-11-21 23:14 ` Charles Forsyth
2011-11-21 23:18 ` Charles Forsyth
[not found] ` <CAOw7k5it_OV56ZNnPygDjh+rA=xC-+-x+DJuSWBCBRC-XhXECw@mail.gmail.c>
2011-11-22 1:52 ` erik quanstrom
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