Date: Wed, 12 Jan 2011 13:27:40 -0800 From: mdf@FreeBSD.org To: John Baldwin <jhb@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r217330 - head/sys/x86/x86 Message-ID: <AANLkTi=Rx2Gyh-n4SLaK3QSvJEvaS2JOm27SEwidmSwy@mail.gmail.com> In-Reply-To: <201101121621.30371.jhb@freebsd.org> References: <201101122108.p0CL8o3Q012038@svn.freebsd.org> <201101121621.30371.jhb@freebsd.org>
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On Wed, Jan 12, 2011 at 1:21 PM, John Baldwin <jhb@freebsd.org> wrote: > On Wednesday, January 12, 2011 4:08:50 pm Matthew D Fleming wrote: >> Author: mdf >> Date: Wed Jan 12 21:08:49 2011 >> New Revision: 217330 >> URL: http://svn.freebsd.org/changeset/base/217330 >> >> Log: >> =A0 Fix a brain fart. =A0Since this file is shared between i386 and amd6= 4, a >> =A0 bus_size_t may be 32 or 64 bits. =A0Change the bounce_zone alignment= field >> =A0 to explicitly be 32 bits, as I can't really imagine a DMA device tha= t >> =A0 needs anything close to 2GB alignment of data. > > Hmm, we do have devices with 4GB boundaries though. =A0I think I'd prefer= it if > you instead if you did this: > > #if defined(amd64) || defined(PAE) > #define SYSCTL_ADD_BUS_SIZE_T =A0 =A0 =A0 =A0 =A0 SYSCTL_ADD_UQUAD > #else > #define SYSCTL_ADD_BUS_SIZE_T =A0 =A0 =A0 =A0 =A0 SYSCTL_ADD_UINT > #endif > > and then just used SYSCTL_ADD_BUS_SIZE_T() in the code so we could let th= e > members in the bounce zone retain the same types passed to > bus_dma_tag_create(). But would there be a device that can't start DMA except on a 4GB boundary? I thought that's what this member was for. Thanks, matthew
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