Date: Fri, 30 Jul 2004 14:17:13 +0200 From: Maxime Henrion <mux@freebsd.org> To: Maxim Sobolev <sobomax@portaone.com> Cc: sos@freebsd.org Subject: Re: Is there still sufficient reason for hw.ata.atapi_dma being 0 by default? Message-ID: <20040730121713.GG13608@elvis.mu.org> In-Reply-To: <410A3833.7030502@portaone.com>
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Maxim Sobolev wrote: > Since high-speed CD-RW/DVD-RW recorders (32x - 52x) are commodity now > IMO it makes sense to review hw.ata.atapi_dma default of 0, since > apparently PIO mode can't support necessary sustained data transfer > rates anymore. For example I had had problems burning RWs on 16-24x with > several drives in PIO mode, which gone when I've switched to DMA. > > I easily imagine newbies who make a conclusion that "FreeBSD sucks" > after installing FreeBSD and finding that they can't burn CDs, while > other operating system do it without any problems. I think it should be enabled by default when the DMA mode of the ATAPI device is UDMA33 or higher, not when it's WDMA2. The atapi_dma sysctl is off by default to guard against buggy ATAPI devices which are incorrectly reporting themselves as being able to do DMA, however I think this mostly applies to old devices, which won't do UDMA33 or higher. Soren would know better than me though. Cheers, Maximehome | help
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