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SubjectRe: [PATCH] don't create regular files in devfs (fwd)
On Tue, 14 Jan 2003, Christoph Hellwig wrote:

> On Tue, Jan 14, 2003 at 09:34:52AM +0000, Tigran Aivazian wrote:
> > Hi Christoph,
> >
> > I don't know about mtrr (probably does it for the same reason) but the
> > reason why microcode driver uses a regular file is because it needs
> > something that only regular files can provide --- the file size.
> >
> > This is an easy external "signifier" as to whether a successfull microcode
> > update has occurred or not.
>
> It seems to work without that feature on systems that don't have devfs..

Of course it works without it. I never said it is a required feature, only
a very nice to have. Namely:

a) if devfs is available it provides a regular file whose size can be
examined by applications and content read/written without much "fuss". In
particular it is very convenient to say "vi microcode" and examine the
content directly. If it was a device node then this would have been
impossible.

b) if devfs is not available then a limited basic functionality is
provided --- i.e. just update the microcode on CPU(s) and write the log
messages in the kernel log.

Btw, having a size of mtrr is also useful for a similar reason.

Regards
Tigran

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