Date: Sat, 09 Nov 2002 15:10:04 -0600 From: "Alan L. Cox" <alc@imimic.com> To: Jeff Roberson <jroberson@chesapeake.net>, Matthew Jacob <mjacob@feral.com>, Andrew Gallatin <gallatin@cs.duke.edu>, alpha@FreeBSD.ORG, alc@FreeBSD.ORG, John Baldwin <jhb@FreeBSD.ORG> Subject: Re: alpha: top of tree kernel blooie Message-ID: <3DCD79AC.AAED8D2A@imimic.com> References: <20021109150359.B97372-100000@mail.chesapeake.net> <3DCD7244.DEEA7387@imimic.com>
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"Alan L. Cox" wrote: > ... > 2. Don't we compile by default for the older Alphas that lack byte > manipulation instructions? Thus, a byte store is implemented by a > read-modify-write sequence of instructions. Thus, two simultaneous > uma_dbg_alloc()s on adjacent locations in us_freelist could cause > corruption. > Specifically, here's the code sequence for the assignment of 255 to us_freelist[] in uma_dbg_alloc() when compiling for ev5: 47c: 0b 00 43 2c ldq_u t1,11(t2) 480: 2b 00 7b 23 lda t12,43(t12) 484: 42 00 5b 48 mskbl t1,t12,t1 488: ff ff 3f 20 lda t0,-1 48c: 61 01 3b 48 insbl t0,t12,t0 490: 01 04 22 44 or t0,t1,t0 494: 0b 00 23 3c stq_u t0,11(t2) Regards, Alan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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