Re: [PATCH v4 02/26] arm64: cpufeature: Add cpufeature for IRQ priority masking
From: Julien Thierry
Date: Fri May 25 2018 - 08:00:39 EST
On 25/05/18 11:41, Suzuki K Poulose wrote:
On 25/05/18 11:39, Julien Thierry wrote:
On 25/05/18 11:36, Suzuki K Poulose wrote:
On 25/05/18 11:17, Julien Thierry wrote:
On 25/05/18 11:04, Suzuki K Poulose wrote:
On 25/05/18 10:49, Julien Thierry wrote:
Add a cpufeature indicating whether a cpu supports masking interrupts
by priority.
How is this different from the SYSREG_GIC_CPUIF cap ? Is it just
the description ?
More or less.
It is just to have an easier condition in the rest of the series.
Basically the PRIO masking feature is enabled if we have a GICv3
CPUIF working *and* the option was selected at build time. Before
this meant that I was checking for the GIC_CPUIF cap inside #ifdefs
(and putting alternatives depending on that inside #ifdefs as well).
Having this as a separate feature feels easier to manage in the
code. It also makes it clearer at boot time that the kernel will be
using irq priorities (although I admit it was not the initial
intention):
[ÂÂÂ 0.000000] CPU features: detected: IRQ priority masking
But yes that new feature will be detected only if SYSREG_GIC_CPUIF
gets detected as well.
Well, you could always wrap the check like :
static inline bool system_has_irq_priority_masking(void)
{
ÂÂÂÂÂreturn (IS_ENABLED(CONFIG_YOUR_CONFIG) &&
cpus_have_const_cap(HWCAP_SYSREG_GIC_CPUIF));
}
and use it everywhere.
Yes, but I can't use that in the asm parts that use alternatives and
would need to surround them in #ifdef... :\
I thought there is _ALTERNATIVE_CFG() to base the alternative depend on
a CONFIG_xxx ?
Doesn't that solve the problem ?
Right, I didn't see that one. It should work yes.
I'll try that when working on the next version.
Thanks,
--
Julien Thierry