From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4DAD572D.9070309@domain.hid> Date: Tue, 19 Apr 2011 11:34:37 +0200 From: Jesper Christensen MIME-Version: 1.0 References: <4D9F0679.7080109@domain.hid> <1302268379.2101.35.camel@domain.hid> <4DA30C80.3010107@domain.hid> <1302531493.2054.355.camel@domain.hid> <4DA30E14.6070401@domain.hid> <1302532049.2054.357.camel@domain.hid> <4DA31108.9080000@domain.hid> <1302532753.2054 <4DA314F1.3070504@domain.hid> <4DA31EB6.4040909@domain.hid> <4DA4544F.7020300@domain.hid> <4DA45660.4000003@domain.hid> <4DA45D0F.4090501@domain.hid> <4DA45E42.5030500@domain.hid> <4DA45FD7.9000802@domain.hid> <4DAD392D.7030501@domain.hid> <1303198745.2096.8.camel@domain.hid> <4DAD40B7.5000803@domain.hid> <1303200143.2096.11.camel@domain.hid> <4DAD4ADA.4040007@domain.hid> <1303205379.2096.34.camel@domain.hid> <1303205415.2096.35.camel@domain.hid> In-Reply-To: <1303205415.2096.35.camel@domain.hid> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-core] kernel threads crash List-Id: Xenomai life and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: xenomai@xenomai.org Okay /Jesper On 2011-04-19 11:30, Philippe Gerum wrote: > On Tue, 2011-04-19 at 11:29 +0200, Philippe Gerum wrote: > >> On Tue, 2011-04-19 at 10:42 +0200, Gilles Chanteperdrix wrote: >> >>> Philippe Gerum wrote: >>> >>>> On Tue, 2011-04-19 at 09:58 +0200, Jesper Christensen wrote: >>>> >>>>> Great thanks, but i can't help wondering if the problems i'm seeing are >>>>> related to some of my userspace programs using fp. >>>>> >>>> I don't think so. The switchtest programs exercises the FPU hardware in >>>> a certain way to make sure it is available in real-time mode from kernel >>>> space (which is an utterly crappy legacy, but we will have to deal with >>>> it until Xenomai 3.x). As far as I can see from your .config, you can't >>>> have such support, so switchtest was basically trying to test an >>>> inexistent feature. >>>> >>> In fact, switchtest whether Xenomai FPU switch routines work when the >>> Linux kernel itself uses FPU in kernel-space. Currently, the only place >>> when this happens is in the RAID code: x86 uses mmx/sse, and some power >>> pcs use altivec. Some powerpc also fix unaligned accesses to floating >>> point data in kernel-space, I do not know if this may interfere, which >>> is why the powerpc code is compiled even without RAID. >>> >>> >>> >> AFAICS, fp_regs_set() on ppc is issuing a load float instruction in >> kernel space which could be unaligned, and therefore trap. Looking at >> the .config for the target system, hw FPU support is disabled in the >> alignment code, so basically, this would beget a nop. >> > A nop in fixing the issue, I mean. > >