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Date:   Tue, 28 Sep 2021 06:39:29 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Sohil Mehta <sohil.mehta@intel.com>
Cc:     x86@kernel.org, Tony Luck <tony.luck@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@kernel.org>,
        Jens Axboe <axboe@kernel.dk>,
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        Gayatri Kammela <gayatri.kammela@intel.com>,
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        linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
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Subject: Re: [RFC PATCH 06/13] x86/uintr: Introduce uintr receiver syscalls
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On Mon, Sep 27, 2021 at 04:20:25PM -0700, Sohil Mehta wrote:
> On 9/23/2021 5:26 AM, Greg KH wrote:
> > On Mon, Sep 13, 2021 at 01:01:25PM -0700, Sohil Mehta wrote:
> > > +
> > > +/* User Posted Interrupt Descriptor (UPID) */
> > > +struct uintr_upid {
> > > +	struct {
> > > +		u8 status;	/* bit 0: ON, bit 1: SN, bit 2-7: reserved */
> > > +		u8 reserved1;	/* Reserved */
> > > +		u8 nv;		/* Notification vector */
> > > +		u8 reserved2;	/* Reserved */
> > What are these "reserved" for?
> 
> 
> The UPID is an architectural data structure defined by the hardware. The
> reserved fields are defined by the hardware (likely to keep the structure
> size as 16 bytes).

Then those values must be set to 0, right?  I think I missed the part of
the code that set them, hopefully it's somewhere...

thanks,

greg k-h