Date: Wed, 26 Apr 2006 00:04:08 -0600 From: Scott Long <scottl@samsco.org> To: Matthew Jacob <mj@feral.com> Cc: src-committers@FreeBSD.org, jhb@FreeBSD.org, Bruce Evans <bde@zeta.org.au>, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org, Warner Losh <imp@bsdimp.com> Subject: Re: cvs commit: src/sys/dev/bce if_bcereg.h Message-ID: <444F0D58.9020000@samsco.org> In-Reply-To: <20060425224750.K65869@ns1.feral.com> References: <444E7750.206@samsco.org> <200604251540.00170.jhb@freebsd.org> <444E7BFE.4040800@samsco.org> <20060425.173236.74726638.imp@bsdimp.com> <444EB6A1.3060901@samsco.org> <20060426103623.M1847@epsplex.bde.org> <20060425223519.F65802@ns1.feral.com> <444F0923.8050508@samsco.org> <20060425224750.K65869@ns1.feral.com>
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Matthew Jacob wrote: >>> >>> I'm afraid I don't understand the 'unreasonable' argument here. Linux >>> is eating your lunch today. Do you want it to eat your dessert as well? >>> >>> -matt >>> >> >> bus_size_t is used for things like measuring transfer segment size. >> There is little chance that Linux, Windows, FreeBSD, or any other OS >> is ever going to try to DMA more than 2^32 bytes of data in a single >> bus transaction. Maybe you could contrive a silly infiniband device >> to do it. Anyways, it has no bearing on whether the CPU, memory >> controller, or PCI buses can do 64 bit addressing. > > > Oh, sorry, yes, I agree it's *unlikely* that anything will DMA more than > 2^32 bytes at a time right now. I'm really really tired and lost lock. > Sorry. > And actually, it's 100% impossible to do a transfer larger than 2^32 on PCI Express due to the protocol requiring that a transfer not cross a 4GB boundary. So, I think that we are pretty safe with this typedef for the next 5-10 years. Of course, I'll be honored when Linus calls me a moron for this 7 years from now =-) Scott
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