On 12/06/18 14:46, Julien Thierry wrote:
On 25/05/18 11:48, Julien Thierry wrote:
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):
[ 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)
{
return (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.
I've been trying to use this now, but I can't figure out how.
The _ALTERNATIVE_CFG does not seem to work in assembly code (despite having its
own definition for __ASSEMBLY__), and the alternative_insn does not seem to be
suited for instructions that take operands (or more than one operand)
If I am mistaken, can you provide an example of how to use this in assembly
with instructions having more than 1 operand?
I am sorry, but I think the ALTERNATIVE_CFG is not the right one, as it
omits the entire block, if the CONFIG is not enabled. So you are left with
only three choices :
1) Use alternative call back
2) Stick to two separate caps.
3) Use #ifdef
Cheers
Suzuki
