Re: [ANNOUNCE] block device interfaces changes

From: Kai Henningsen (kaih@khms.westfalen.de)
Date: Sun Jan 09 2000 - 14:02:00 EST


alan@lxorguk.ukuu.org.uk (Alan Cox) wrote on 09.01.00 in <E127IVH-0001kh-00@the-village.bc.nu>:

> > [User mode interface]
> > int devicecontrol(int filehandle, unsigned command,
> > size_t insize, void *inbuf,
> > size_t outsize, void *outbuf);
> >
> > That is, the parameters clearly indicate which access is allowed to what
> > memory, and how big buffers are. The old ioctl() interface could translate
>
> This wouldn't be flexible enough. Many ioctls pass multiple objects around.

"Many"? Which would those be? Haven't seen any yet.

> For the standard form the existing ioctls encode their size.

Except that there are tons of legacy ioctls that don't ...

>Also since the
> copy*user* stuff does inbuilt fault handling and we need to know the object
> size for the copy it has no code size improvement

Code size?! I see no reason to even think about that in this context.

> devicecontrol in the form you give has no value outside a message passing
> microkernel.

Somehow, my memory tells me that people (including Linus) liked something
very similar a short time back ...

MfG Kai

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