Hi Hanjun, On 01/03/17 08:27, Hanjun Guo wrote: > On 2017/2/28 21:22, James Morse wrote: >> On 27/02/17 18:19, Shiju Jose wrote: >>> Add a new GHES error source handling function for >>> GSIV(Global System Interrupt Vector). >>> If an error source's notification type is GSIV, >>> then this handling function can be registered >>> into the GSIV handler and it can parse >>> and report error information when they occur. >> >> I'm missing some of the story here, but how is GSIV different from 'External >> Interrupt'? I'm guessing something other than the CPU takes this 'interrupt'... > > Yes, it's the same from CPU side (they are interrupts!), but there > is history behind them and the usage is different. > > I think External Interrupt was introduced before ACPI is available on > ARM (hardware reduced platforms), so I guess it was used for errors > reported to OS which were not using SCI mechanism, for example, some > IO error reporting. > > For External Interrupt, we don't use the ACPI event system, so for > the firmware, it just report the errors associate with the interrupt > number, the kernel map the interrupt number and install the > irq handler for it. > > For GSIV based event, it was introduced for hardware reduced platform > in recent ACPI revision, and ARM64 is one of its consumers. When > errors are reported via GSIV, ACPI event notification needs to be > implemented and requires the platform to define a hardware error device > (PNP0C33) in ACPI namespace, and also a generic event device ACPI0013. Okay, so for APEI this really means PNP0C33 was Notify()d. 'SCI' means the same but the route they take to get into APEI is different. > For example, if we are using SPI (ARM GIC) 100 to report errors, there > is a ACPI0013 driver in drivers/acpi/evged.c to register the irq, when Aha, this is where the interrupt-magic happens. > error happened and trigger the interrupt, ACPI0013 driver will > notify the error device (PNP0C33), then error device driver > (drivers/acpi/hed.c) will process the error data form APEI table... >> The GHES GSIV code below is identical to the behaviour of the SCI Notification >> type... are these two names for the same thing? (I'm confused!) > > SCI is also an 'interrupt' but it's a special irq number for ACPI > event, and it has GPE (general purpose event) registers behind it, > which is used only on Intel platforms. SCI based event use > Method(\_GPE._L0x) to notify the error device (PNP0C33), but GSIV > is used for HW-reduced platform which has no GPEs. > Hope it can clarify something :) Yes thanks! (the mist is slowly clearing...) If ACPI_HEST_NOTIFY_SCI and ACPI_HEST_NOTIFY_GSIV both mean 'receive notification from PNP0C33', is there any point having separate lists and add/remove functions for them? Instead, could we rename Linux's ghes_notifier_sci() and ghes_sci list to describe 'hed' instead, then group the two case statements together? There would be no need to add a selectable CONFIG_ACPI_APEI_GSIV, as SCI is already built-in and this way the code added is tiny. The only thing we would lose is the name 'GSIV' in the not-supported error message which we don't need if its always supported. Thanks, James _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
