Messages in this thread | | | Date | Wed, 11 Jan 2006 10:55:07 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH]trivial: add CDC_RAM to ide-cd capabilities mask |
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On Wed, Jan 11 2006, Andrey Borzenkov wrote: > > > -----Original Message----- > From: Jens Axboe <axboe@suse.de> > To: Andrey Borzenkov <arvidjaar@mail.ru> > Date: Wed, 11 Jan 2006 10:29:38 +0100 > Subject: Re: [PATCH]trivial: add CDC_RAM to ide-cd capabilities mask > > > > > On Wed, Jan 11 2006, Andrey Borzenkov wrote: > > > > > > > > > > drive name: sr0 > > > > drive speed: 1 > > > > drive # of slots: 1 > > > > Can close tray: 1 > > > > Can open tray: 1 > > > > Can lock tray: 1 > > > > Can change speed: 0 > > > > Can select disk: 0 > > > > Can read multisession: 1 > > > > Can read MCN: 1 > > > > Reports media changed: 1 > > > > Can play audio: 1 > > > > Can write CD-R: 0 > > > > Can write CD-RW: 0 > > > > Can read DVD: 0 > > > > Can write DVD-R: 0 > > > > Can write DVD-RAM: 0 > > > > Can read MRW: 1 > > > > Can write MRW: 1 > > > > Can write RAM: 1 > > > > > > > > There's no way this drive knows anything about MRW or random-access writing: > > > > > > > ... > > > > And an ATAPI DVD-ROM also reports (before the above patch): > > > > > > > > Can read MRW: 1 > > > > Can write MRW: 1 > > > > Can write RAM: 1 > > > > > > > > > > I know. There were patches from Jens for both 2.4 and 2.6 that add MRW > > > support to ide-cd for sure; may be for sr too, am not sure. Jens, any > > > reasons for them not in mainstream? Otherwise probably ide-cd and sr should > > > not announce MRW capabiliies at all, it is too confusing; I'll send a patch > > > when I am at home. > > > > MRW support is in 2.6 since ages. The MRW flag is only detected on open, > > so it should disappear from the proc file once you have opened the > > drive. It has to be done that way, I'm afraid. > > > > I see, it is in generic cdrom code, sorry. > > is it possible that drive supports MRW_W without supporting any other write > method (_R/_RW)? Should not ide-cd/sr - or possibly even cdrom - mask MRW_W > if they do not support writing at all?
I don't know why anyone would make such a device, but of course it's possible. Masking MRW if the device can't write sounds like a safe enough bet, I'll take a patch :)
-- Jens Axboe
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