"use register arguments" option enabled.

Mike Honeyfield mike.honeyfield at gmail.com
Tue May 17 07:29:55 UTC 2005


On 5/17/05, Arjan van de Ven <arjanv at redhat.com> wrote:
> On Tue, 2005-05-17 at 10:45 +1200, Mike Honeyfield wrote:
> > On 5/17/05, Ignacio Vazquez-Abrams <ivazquez at ivazquez.net> wrote:
> > > On Tue, 2005-05-17 at 10:29 +1200, Mike Honeyfield wrote:
> > > > I am just wondering the reasoning behind having the experimental
> > > > option "Use register arguments" on in the kernel config.
> > > >
> > > > It has caused some issues for me, have since fixed it, but was
> > > > wondering why an experimental feature that could/can break the ABI for
> > > > 3rd party binary only modules would be enabled?
> > >
> > > Speed. Pushing data onto the stack takes longer than just shoving it
> > > into a register.
> > >
> >
> > So the speed improvement is enough to justify this?
> >
> > I could understand Fedora Core's kernels have this feature, but was a
> > bit suprised to see the same issue in RHEL.
> 
> why?
> 
> This only impacts binary modules, and in the process of porting those to
> 2.6 the vendor needs to "fix" this up just as well. That is the same for
> FC and RHEL.
> 

So you disagree that this is actually "experimental" as per the kernel config? 

Doesn't the term experimental indirectly imply possible stability
issues? Not reasuring IMHO.

Yes, RH's choice in kernel configure option is theirs and yes, it is
true, binary only vendor can "fix" (not sure waht the quotes imply),
we have "fixed" our drivers. Worth noting, our driver was written for
2.6 and in RHEL it was broken, but not other platforms we support,
like debian and suse.

However, I was curious because it seemed ironic to possibly break ABI
for binary only vendors in the enterprise product.

This might be a bold assumption to make, but from the market I have
seen where RHEL fits in, people are using closed sourced apps and
drivers because that apps they need run on RHEL or are offically
supported on RHEL. So it seems odd that one of the reasons that
someone would use RHEL could also be the reason they cant run that
app/driver.

Hence my comment, I understood FC, but not RHEL. 

Cheers

Mike




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