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Date: Mon, 04 Jan 2010 16:16:06 -0800 From: Yinghai Lu <yinghai@...nel.org> To: Suresh Siddha <suresh.b.siddha@...el.com> CC: "H. Peter Anvin" <hpa@...or.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, Jesse Brandeburg <jesse.brandeburg@...il.com>, Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, NetDEV list <netdev@...r.kernel.org>, "Brandeburg, Jesse" <jesse.brandeburg@...el.com> Subject: Re: Subject: [PATCH 1/2] x86: get back 15 vectors On 01/04/2010 04:05 PM, Suresh Siddha wrote: > On Mon, 2010-01-04 at 11:50 -0800, H. Peter Anvin wrote: >> On 01/04/2010 11:45 AM, Suresh Siddha wrote: >>> On Mon, 2010-01-04 at 11:35 -0800, Yinghai Lu wrote: >>>> sth like this? >>>> >>>> Subject: [PATCH 1/2] x86: get back 16 vectors >>>> >>>> -v2: according to hpa that we could start from 0x10 >>>> according to Eric, we should hold 16 vectors for IRQ MOVE >>>> >>>> Signed-off-by: Yinghai Lu <yinghai@...nel.org> >>>> >>> >>> Yinghai we have to change IRQ_MOVE_CLEANUP_VECTOR to 0x1f or so. From >>> the cpu perspective this vector is documented as illegal, so we need to >>> check if this change will work on the cpu's we have today to get some >>> confidence. >>> >> >> It's documented as reserved, not illegal. The ability for the APIC to >> generate vectors starting at 0x10 is documented, as is the ability for >> the CPU to receive any vector number as an interrupt -- in fact, the >> legacy BIOS relies on being able to receive interrupts starting at >> vector 0x08. It causes problems galore, but only at the software level. > > I have checked out couple of platforms (including 32-bit atom) and 0x1f > vector logic seems to be working. > > Hopefully we won't have other hardware or software issues (vmm > restrictions etc) with this logic. > good. hope it is final version. let's have hpa own it. From: "H. Peter Anvin" <hpa@...or.com> Subject: [PATCH] x86: get back 16 vectors -v2: according to hpa that we could start from 0x1f -v3: update comments from Eric -v4: update comments from hpa -v5: use round up for IRQ0_VECTOR according to hpa Signed-off-by: Yinghai Lu <yinghai@...nel.org> --- arch/x86/include/asm/irq_vectors.h | 40 ++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 14 deletions(-) Index: linux-2.6/arch/x86/include/asm/irq_vectors.h =================================================================== --- linux-2.6.orig/arch/x86/include/asm/irq_vectors.h +++ linux-2.6/arch/x86/include/asm/irq_vectors.h @@ -30,26 +30,38 @@ /* * IDT vectors usable for external interrupt sources start * at 0x20: + * hpa said we can start from 0x1f. + * 0x1f is documented as reserved. However, the ability for the APIC + * to generate vectors starting at 0x10 is documented, as is the + * ability for the CPU to receive any vector number as an interrupt. + * 0x1f is used for IRQ_MOVE_CLEANUP_VECTOR since that vector needs + * an entire privilege level (16 vectors) all by itself at a higher + * priority than any actual device vector. Thus, by placing it in the + * otherwise-unusable 0x10 privilege level, we avoid wasting a full + * 16-vector block. */ -#define FIRST_EXTERNAL_VECTOR 0x20 +#define FIRST_EXTERNAL_VECTOR 0x1f +#define IA32_SYSCALL_VECTOR 0x80 #ifdef CONFIG_X86_32 # define SYSCALL_VECTOR 0x80 -# define IA32_SYSCALL_VECTOR 0x80 -#else -# define IA32_SYSCALL_VECTOR 0x80 #endif /* - * Reserve the lowest usable priority level 0x20 - 0x2f for triggering + * Reserve the lowest usable priority level 0x10 - 0x1f for triggering * cleanup after irq migration. + * this overlaps with the reserved range for cpu exceptions so this + * will need to be changed to 0x20 - 0x2f if the last cpu exception is + * ever allocated. */ + #define IRQ_MOVE_CLEANUP_VECTOR FIRST_EXTERNAL_VECTOR /* - * Vectors 0x30-0x3f are used for ISA interrupts. + * Vectors 0x20-0x2f are used for ISA interrupts. + * round up to the next 16-vector boundary */ -#define IRQ0_VECTOR (FIRST_EXTERNAL_VECTOR + 0x10) +#define IRQ0_VECTOR ((FIRST_EXTERNAL_VECTOR + 16) & ~15) #define IRQ1_VECTOR (IRQ0_VECTOR + 1) #define IRQ2_VECTOR (IRQ0_VECTOR + 2) -- 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/
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