linux-kernel - Re: Does it need to implement irq_set_type method in the ioapic

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fe0610e4-0073-42a7-803a-590de82e47ef@email.android.com>
Date:	Tue, 18 Feb 2014 18:34:38 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	carl peng <carlpeng008@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
CC:	mingo@...hat.com, x86@...nel.org, pingfank@...ux.vnet.ibm.com,
	yoshihiro.yunomae.ez@...achi.com, linux-kernel@...r.kernel.org
Subject: Re: Does it need to implement irq_set_type method in the ioapic_chip?

This is an ACPI device connecting to an internal IOAPIC? If not, how is it connected?

On February 18, 2014 6:32:44 PM PST, carl peng <carlpeng008@...il.com> wrote:
>Hi Thomas,
>
>Thanks a lot for your help!
>
>But I still have some confusion. Could you please help to give some
>suggestions to me?
>
>1) This device is a ACPI device, the hardware engineer designed it as
>falling edge interrupt trigger
>mode, does it need to re-work the hardware and modify it as rising
>edge trigger mode to suit the
>Linux APIC driver architecture?
>2) Why does APIC driver not implement the irq_set_type method?  if
>implement it, will supply more
>free space for the device driver developer(they can set the interrupt
>trigger mode by calling request_irq).
>
>Thank you!
>Carl
>
>
>On Wed, Feb 19, 2014 at 4:13 AM, Thomas Gleixner <tglx@...utronix.de>
>wrote:
>> On Tue, 18 Feb 2014, carl peng wrote:
>>
>> Carl, sending the same mail twice within an hour does not speed up
>> things. It's quite likely that it gets ignored.
>>
>>> 1. Does it need to implement irq_set_type method in the ioapic_chip
>>> structure?
>>
>> No. The irq type is configured by the type of the interrupt or the
>> BIOS.
>>
>> ISA  interrupts are always polarity zero edge triggered (historic)
>>
>> PCI  interrupts are always polarity one level triggered
>>
>> PCIE interrupts are either legacy PCI or with MSI[X] always edge
>>      triggered
>>
>>> 2. if no need to implement it, how can device driver set the trigger
>mode
>>> of APIC interrupt controller pin?
>>
>> Not at all.
>>
>> The device which is connected to one of the busses must follow the
>> specification of the bus. There is no choice. Any additional
>> requirements of the device to deal with external signals must be
>> handled by the device itself and converted to the appropriate bus
>> requirement.
>>
>> This all is configured by the kernel automatically through bus
>> detection and BIOS tables.
>>
>> Thanks,
>>
>>         tglx

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/