Re: MSI/MSI-X implementation and interrupt handling on i386/amd64

[Kimihiro Nonaka <nonakap%gmail.com@localhost>]

Hi,

I updated jdolecek's patch.

https://gist.github.com/nonakap/05fb8d73a58cfe189128bb1f837d8203

On Sat, Dec 15, 2018 at 3:55 AM Jaromír Doleček
<jaromir.dolecek%gmail.com@localhost> wrote:
>
> Le mar. 11 déc. 2018 à 23:41, Jaromír Doleček
> <jaromir.dolecek%gmail.com@localhost> a écrit :
> > I'm investigating an initial solution which will keep the
> > ipending+ilevel still as 64-bit quantity suitable for cmpxchg8b, using
> > 4 bits for the ilevel and remaining 60 for ipending.
>
> I have some intermediary code which compiles, but likely not yet works
> (not tested yet):
>
> https://www.netbsd.org/~jdolecek/x86_intr_cpu56.diff
>
> I went for for 8/56 split for ilevel/ipending, because it makes the
> coding way more convenient - no masks and shifts necessary, can fetch
> ilevel with just 'movb' and then the whole thing with 'movq'.
>
> In IDTVEC() I've replaced
>   orl $(1 << num),CPUVAR(IPENDING)
> with
>   btsq $(num),CPUVAR(...)
>
> since 'orq' doesn't support 64-bit immediate argument. For zeroing the
> top 8bit for ipending I've used 'andq' with mask in register.
>
> I've replaced the atomic_and_32() in intr.c with just membar_sync()
> before and after, so that the code doesn't need 64-bit atomic ops. In
> fact I'm not really convinced it's necessary at all - the code
> disables all interrupts before executing this, so perhaps the
> synchronization is not needed at all?
>
> Jaromir