Date: Thu, 29 Jul 2010 19:57:33 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: pebu3op@googlemail.com Cc: freebsd-hackers@freebsd.org Subject: Re: coherence-problem on the mapped memory buffer Message-ID: <4C51B2FD.6070702@icyb.net.ua> In-Reply-To: <4C51A8A3.7080808@icyb.net.ua> References: <201007291613.15719.pebu3op@googlemail.com> <4C51A8A3.7080808@icyb.net.ua>
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on 29/07/2010 19:13 Andriy Gapon said the following: > on 29/07/2010 17:13 Alexander Fiveg said the following: >> P.S. Details about hardware and used software: >> 1. /var/run/dmesg.boot : >> ... >> CPU: Dual Core AMD Opteron(tm) Processor 865 (1800.01-MHz 686-class CPU) >> Origin = "AuthenticAMD" Id = 0x20f10 Family = f Model = 21 Stepping = 0 >> >> Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT> >> Features2=0x1<SSE3> >> AMD Features=0xe2500800<SYSCALL,NX,MMX+,FFXSR,LM,3DNow!+,3DNow!> >> AMD Features2=0x3<LAHF,CMP> >> real memory = 3758030848 (3583 MB) >> avail memory = 3677495296 (3507 MB) >> ACPI APIC Table: <A M I OEMAPIC > >> FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs >> FreeBSD/SMP: 4 package(s) x 2 core(s) >> ... >> >> 2. uname -v >> FreeBSD 9.0-CURRENT #3 >> >> 3. sysctl kern.osreldate >> kern.osreldate: 900014 >> >> 4. //depot/projects/soc2010/ringmap/ In fact I have a suspicion that the problem might have to do with multiple mappings of the shared pages, but far from sure... Take a look at Intel® 64 and IA-32 Architectures Software Developer’s Manual Volume 3A - System Programming Guide, Part 1; Chapter 11.12.4 Programming the PAT; starting at the following words: «The PAT allows any memory type to be specified in the page tables, and therefore it is possible to have a single physical page mapped to two or more different linear addresses, each with different memory types. Intel does not support this practice...» -- Andriy Gapon
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