On Tue, 03 Jan 2023 16:45:04 +0000,
Mukesh Ojha <quic_mojha@xxxxxxxxxxx> wrote:
Hi,
Thanks for your reply.
On 1/2/2023 10:41 PM, Marc Zyngier wrote:
Hi Mukesh,
On Mon, 02 Jan 2023 16:44:59 +0000,
Mukesh Ojha <quic_mojha@xxxxxxxxxxx> wrote:
Hi Marc,
I was looking similar support mentioned in below patch series.
https://lore.kernel.org/lkml/CAFA6WYO0+LQ=mB1spCstt0cNZ0G+sZu_+Wrv6BKSeXqF5SRq4A@xxxxxxxxxxxxxx/#t
Wanted to check if there is chance of these patches to land in
mainline ?
I certainly have no intention to merge it as is, specially as there is
no good usage model for it other than "but think of debug!".
We have exactly *one* SGI left. If we are going to lose it over such a
feature, I'd want a description of how we are going to share it
between potential users, and how we claw some currently used SGIs
back.
But, looks like patch will fail if SGI is not available.
https://lore.kernel.org/lkml/1604317487-14543-4-git-send-email-sumit.garg@xxxxxxxxxx/
set_smp_ipi_range(base_sgi, 8);
+ if (n > nr_ipi)
+ set_smp_dynamic_ipi(ipi_base + nr_ipi);
+
So, static SGI allocation still has higher priority than dynamic
one. Would you be accepting if we keep it under some
CONFIG_ARM64_IPI_NMI_DEBUG ?
But why should this thing have priority over other potential features?
As I said above, there are two requirements:
- being able to share a single NMI SGI amongst multiple users
- being able to free existing SGIs in case we absolutely need an SGI
for some other purposes
In both cases, this is about making the SGI space scale *beyond* the 8
possible interrupts that we have. This needs to be solved to get
something like this in.
And I don't think hiding this behind an obscure "debug" configuration
option that will get abused with out of tree stuff is a good move.
Quite the opposite.
Thanks,
M.