Messages in this thread |  | | | Subject | Re: Subject: [PATCH 1/2] x86: get back 15 vectors | | From | (Eric W. Biederman) | | Date | Mon, 04 Jan 2010 11:09:05 -0800 |
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"H. Peter Anvin" <hpa@zytor.com> writes:
> On 01/04/2010 08:18 AM, Eric W. Biederman wrote: >> Yinghai Lu <yinghai@kernel.org> writes: >> >> This patch is wrong. >> >>> between FIRST_EXTERNAL_VECTOR (0x20) and FIRST_DEVICE_VECTOR (0x41) >>> >>> for 0x20 and 0x2f, we are safe be used_vectors will prevent it to use used one. >> >> We can not use any of 0x20 - 0x2f for ioapic irqs. We need the entire >> priority level to ensure that the irq move cleanup ipi is of a lower >> priority. >> > > Almost makes one want to abuse 0x1f for that. Although 0x00..0x1f are > reserved for exceptions, the APICs range down to 0x10, and well, when > 0x1f ends up actually getting used as an exception vector that we > support, then we can trivially change that. In the meantime it would > actually make use of an otherwise-unusable APIC priority level.
An optimization like that (with a big fat comment) seems reasonable to me.
Eric
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