Date: Mon, 14 Aug 2000 12:57:54 +1200 From: "MATTHEW JOHN,LUCKIE" <mjl12@waikato.ac.nz> To: alpha@FreeBSD.ORG Cc: jdp@polstra.com Subject: RE: kernel modules/unaligned access fault Message-ID: <45E87454FFC2D211AD9800508B65009420F8E4@stu-ex1.waikato.ac.nz>
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thanks for this everything seems to go ok now with the bcopy would you mind explaining to me the rules of programming for the alpha in terms of unaligned accesses. the original version of the code went getnanotime(&pr->ts); and then i byte ordered the members of the struct at a later date - all inside the mbuf->m_data but i got the uac fault at the call to the getnanotime. I would just be interested to know a bit more so i can optimise my code a bit more rather than copy data where i perhaps might not need to. thanks again Matthew > -----Original Message----- > From: John Polstra [SMTP:jdp@polstra.com] > Sent: Monday, August 14, 2000 5:44 AM > To: alpha@freebsd.org > Cc: mjl12@waikato.ac.nz > Subject: Re: kernel modules/unaligned access fault > > In article <45E87454FFC2D211AD9800508B650094BA4E3E@stu-ex1.waikato.ac.nz>, > MATTHEW JOHN,LUCKIE <mjl12@waikato.ac.nz> wrote: > > > > I am running into problems with the timestamping, whereby i am getting > an > > unaligned access fault panic. > > I am making a call to getnanotime, with the results getting copied into > a > > bit of data in the mbuf that is offset 48 bytes in the packet > [...] > > m->m_data += 4; /* 44 bytes offset */ > > pr = mtod(m, struct pathrecord *pr); > > pr->ip = 0; > > getnanotime(&ts); > > ts.ts_sec = htonl(ts.ts_sec); > > ts.ts_nsec = htonl(ts.ts_nsec); > > pr->ts = ts; /* crashes in this line, 44 bytes offset from m_data */ > > Instead of assigning it directly like that, use bcopy() to copy it > into place. > > bcopy(&ts, &pr->ts, sizeof ts); > > John > -- > John Polstra > jdp@polstra.com > John D. Polstra & Co., Inc. Seattle, Washington > USA > "Disappointment is a good sign of basic intelligence." -- Chögyam > Trungpa To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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