Date: Mon, 20 Mar 2000 19:12:22 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: current@FreeBSD.ORG Subject: Re: patches for test / review Message-ID: <19790.953575942@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 20 Mar 2000 09:36:22 PST." <200003201736.JAA70124@apollo.backplane.com>
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In message <200003201736.JAA70124@apollo.backplane.com>, Matthew Dillon writes: > I think so. I can give -current a quick synopsis of the plan but I've > probably forgotten some of the bits (note: the points below are not > in any particular order): Thanks for the sketch. It sounds really good. Is it your intention that drivers which cannot work from the b_pages[] array will call to map them into VM, or will a flag on the driver/dev_t/ whatever tell the generic code that it should be mapped before calling the driver ? What about unaligned raw transfers, say a raw CD read of 2352 bytes from userland ? I pressume we will need an offset into the first page for that ? One thing I would like to see is for the buffers to know how to write themselves. There is nothing which mandates that a buffer be backed by a disk-like device, and there are uses for buffers which aren't. Being able to say bp->bop_write(bp) rather than bwrite(bp) would allow that flexibility. Kirk already introduced a bio_ops[] but made it global for now, that should be per buffer and have all the bufferops in it, (except for the onces which instantiate the buffer). If we had this, pseudo filesystems like DEVFS could use UFS for much of their naming management. This is currently impossible. -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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