Date: Wed, 12 Jan 2011 16:10:29 -0800 From: mdf@FreeBSD.org To: Bruce Evans <brde@optusnet.com.au> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r217330 - head/sys/x86/x86 Message-ID: <AANLkTi=ub6-r977Jag3Lt3wdauw1dQaBvGv7TpMu3L-s@mail.gmail.com> In-Reply-To: <20110113104728.L1003@besplex.bde.org> References: <201101122108.p0CL8o3Q012038@svn.freebsd.org> <201101121621.30371.jhb@freebsd.org> <20110113104728.L1003@besplex.bde.org>
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On Wed, Jan 12, 2011 at 4:06 PM, Bruce Evans <brde@optusnet.com.au> wrote: > On Wed, 12 Jan 2011, John Baldwin wrote: > >>> Log: >>> Fix a brain fart. Since this file is shared between i386 and amd64, a >>> bus_size_t may be 32 or 64 bits. Change the bounce_zone alignment field >>> to explicitly be 32 bits, as I can't really imagine a DMA device that >>> needs anything close to 2GB alignment of data. >> >> Hmm, we do have devices with 4GB boundaries though. I think I'd prefer it >> if >> you instead if you did this: >> >> #if defined(amd64) || defined(PAE) >> #define SYSCTL_ADD_BUS_SIZE_T SYSCTL_ADD_UQUAD >> #else >> #define SYSCTL_ADD_BUS_SIZE_T SYSCTL_ADD_UINT >> #endif >> >> and then just used SYSCTL_ADD_BUS_SIZE_T() in the code so we could let the >> members in the bounce zone retain the same types passed to >> bus_dma_tag_create(). > > U_LONG should work on all arches. malloc(9) still uses u_long instead > of size_t. This works for scalars even on the recently removed i386's > with 32-bit longs where u_long is larger than size_t, since larger is > a fail-safe direction. This fails for pointers. Newer parts of malloc() > and uma are broken unless u_long is the same as uintptr_t, since they > cast pointers to u_long. This direction is fail-safe too, but gcc warns > about it. In this case for PAE u_long is (theoretically) too small, because a bus_size_t is an uint64_t. > uquad_t should never be used, like unsigned long long. Similarly for > signed types. Perhaps it could be removed in sysctl interfaces first. The name SYSCTL_ADD_UQUAD is a little misleading since it's really for a uint64_t. The name could be changed, but there's already plenty of existing uses of QUAD for int64_t which aren't being changed. Thanks, matthew
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