Re: [PATCH 1/5] target/arm: only build psci for TCG

[Alexander Graf]

Hey Fabiano,

On 19.12.22 12:42, Fabiano Rosas wrote:
> Claudio Fontana <cfontana@suse.de> writes:
>
> > Ciao Alex,
> >
> > On 12/19/22 11:47, Alexander Graf wrote:
> > > Hey Claudio,
> > >
> > > On 19.12.22 09:37, Claudio Fontana wrote:
> > > > On 12/16/22 22:59, Alexander Graf wrote:
> > > > > Hi Claudio,
> > > > >
> > > > > If the PSCI implementation becomes TCG only, can we also move to a tcg accel 
> > > > > directory? It slowly gets super confusing to keep track of which files are 
> > > > > supposed to be generic target code and which ones TCG specific>
> > > > > Alex
> > > > Hi Alex, Fabiano, Peter and all,
> > > >
> > > > that was the plan but at the time of:
> > > >
> > > > https://lore.kernel.org/all/20210416162824.25131-1-cfontana@suse.de/
> > > >
> > > > Peter mentioned that HVF AArch64 might use that code too:
> > > >
> > > > https://lists.gnu.org/archive/html/qemu-devel/2021-03/msg00509.html
> > > >
> > > > so from v2 to v3 the series changed to not move the code under tcg/ , expecting HVF to be 
> > > > reusing that code "soon".
> > > >
> > > > I see that your hvf code in hvf/ implements psci, is there some plan to reuse 
> > > > pieces from the tcg implementation now?
> > > I originally reused the PSCI code in earlier versions of my hvf patch
> > > set, but then we realized that some functions like remote CPU reset are
> > > wired in a TCG specific view of the world with full target CPU register
> > > ownership. So if we want to actually share it, we'll need to abstract it
> > > up a level.
> > >
> > > Hence I'd suggest to move it to a TCG directory for now and then later
> > > move it back into a generic helper if we want / need to. The code just
> > > simply isn't generic yet.
> > >
> > > Or alternatively, you create a patch (set) to actually merge the 2
> > > implementations into a generic one again which then can live at a
> > > generic place :)
> > >
> > >
> > > Alex
> > Thanks for the clarification, I'll leave the choice up to Fabiano now, since he 
> > is working on the series currently :-)
> >
> > Ciao,
> >
> > Claudio
> Hello, thank you all for the comments.
>
> I like the idea of merging the two implementations. However, I won't get
> to it anytime soon. There's still ~70 patches in the original series
> that I need to understand, rebase and test, including the introduction
> of the tcg directory.


Sure, I am definitely fine with leaving them separate for now as well :).


> I'd say we merge this as is now, since this patch has no
> dependencies. Later when I introduce the tcg directory I can move the
> code there along with the other tcg-only files. I'll take note to come
> back to the PSCI code as well.

I'm confused about the patch ordering :). Why is it easier to move the 
psci.c compilation target from generic to an if(CONFIG_TCG) only to 
later move it into a tcg/ directory? Wouldn't it be easier to create a 
tcg/ directory from the start and just put it there?

The current approach just looks like duplicate effort to me.


Alex