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Groups > linux.kernel > #1281908
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros |
| Date | 2015-12-02 16:40 +0100 |
| Message-ID | <qBhFD-By-3@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <qB1Ky-7cT-13@gated-at.bofh.it> <qB1Ue-7g2-9@gated-at.bofh.it> <qB23T-7jj-5@gated-at.bofh.it> <qB39D-8en-1@gated-at.bofh.it> <qB5br-11k-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Dec 01, 2015 at 06:21:06PM -0800, Sinclair Yeh wrote:
> On Tue, Dec 01, 2015 at 04:04:08PM -0800, Greg Kroah-Hartman wrote:
> > On Tue, Dec 01, 2015 at 02:54:20PM -0800, Sinclair Yeh wrote:
> > > Hi,
> > >
> > > On Tue, Dec 01, 2015 at 02:45:27PM -0800, Dmitry Torokhov wrote:
> > > > On Tue, Dec 1, 2015 at 2:32 PM, Sinclair Yeh <syeh@vmware.com> wrote:
> > > > > Hi,
> > > > >
> > >
> > > <snip>
> > >
> > > > >> > */
> > > > >> > -#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4) \
> > > > >> > -({ \
> > > > >> > - unsigned long __dummy1, __dummy2; \
> > > > >> > - __asm__ __volatile__ ("inl %%dx" : \
> > > > >> > - "=a"(out1), \
> > > > >> > - "=b"(out2), \
> > > > >> > - "=c"(out3), \
> > > > >> > - "=d"(out4), \
> > > > >> > - "=S"(__dummy1), \
> > > > >> > - "=D"(__dummy2) : \
> > > > >> > - "a"(VMMOUSE_PROTO_MAGIC), \
> > > > >> > - "b"(in1), \
> > > > >> > - "c"(VMMOUSE_PROTO_CMD_##cmd), \
> > > > >> > - "d"(VMMOUSE_PROTO_PORT) : \
> > > > >> > - "memory"); \
> > > > >> > +#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4) \
> > > > >> > +({ \
> > > > >> > + unsigned long __dummy1 = 0, __dummy2 = 0; \
> > > > >>
> > > > >> Why do we need to initialize dummies?
> > > > >
> > > > > Because for some commands those parameters to VMW_PORT() can be both
> > > > > input and outout.
> > > >
> > > > The vmmouse commands do not use them as input though, so it seems we
> > > > are simply wasting CPU cycles setting them to 0 just because we are
> > > > using the new VMW_PORT here. Why do we need to switch? What is the
> > > > benefit of doing this?
> > >
> > > There are two reasons. One is to make the code more readable and
> > > maintainable. Rather than having mostly similar inline assembly
> > > code sprinkled across multiple modules, we can just use the macros
> > > and document that.
> >
> > But the macro is only used here, and the variables aren't used at all,
> > so it makes no sense in this file.
>
> Maybe it's because I didn't CC you on the rest of the series. I wasn't
> sure what the proper distribution list is for each part.
Use scripts/get_maintainer.pl, that's what it is there for. A number of
those patches should go through me, if not all of them, if you want them
merged...
>
> This new macro is also used in arch/x86/kernel/cpu/vmware.c and
> vmw_balloon.c
And it's used inconsistantly in those patches (you don't set the dummy
variables to 0 in all of them...) Now maybe that's just how the asm
functions work, but it's not very obvious as to why this is at all.
> > > The second reason is this organization makes some on-going future
> > > development easier.
> >
> > We don't plan for "future" development other than a single patch series,
> > as we have no idea what that development is, nor if it will really
> > happen. You can always change this file later if you need to, nothing
> > is keeping that from happening.
>
> So the intent of this series is to centralize similar lines of inline
> assembly code that are currently used by 3 different kernel modules
> to a central place. The new vmware.h [patch 0/6] becomes the one header
> to include for common guest-host communication needs.
Why can't it go into vmw_vmci_defs.h instead, or your other .h file, why
create yet-another-.h-file for your bus? You already have 2, this would
make it 3, which seems like a lot...
thanks,
greg k-h
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[PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-01 23:20 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-01 23:30 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-01 23:40 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-01 23:50 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-02 00:00 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-02 01:00 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-12-02 01:10 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-02 03:20 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-12-02 16:40 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-02 17:00 +0100
Re: [Linux-graphics-maintainer] [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Thomas Hellstrom <thellstrom@vmware.com> - 2015-12-02 18:30 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-02 18:30 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-12-02 19:50 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2015-12-02 20:00 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros "Sinclair Yeh" <syeh@vmware.com> - 2015-12-02 20:10 +0100
Re: [Linux-graphics-maintainer] [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Thomas Hellstrom <thellstrom@vmware.com> - 2015-12-02 08:10 +0100
Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-12-02 01:10 +0100
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