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Axe MINIMUM_MSI_INT.

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Just allow MSI interrupts to always start at the end of the I/O APIC
pins.  Since existing machines already have more than 255 I/O APIC
pins, IRQ 255 is no longer reliably invalid, so just remove the
minimum starting value for MSI.

Reviewed by:	kib, markj
Differential Revision:	https://reviews.freebsd.org/D17991
This commit is contained in:
John Baldwin 2018-11-16 23:39:39 +00:00
parent 2343757338
commit e13507f6f0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=340488
4 changed files with 9 additions and 11 deletions
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12
sys/x86/include/intr_machdep.h
View File

@ -51,15 +51,11 @@
* IRQ values returned by ACPI methods such as _CRS can be used
* directly by the ACPI bus driver.
*
* MSI interrupts allocate a block of interrupts starting at either
* the end of the I/O APIC range or 256, whichever is higher. When
* running under the Xen Hypervisor, an additional range of IRQ values
* are available for binding to event channel events. We use 256 as
* the minimum IRQ value for MSI interrupts to attempt to leave 255
* unused since 255 is used in PCI to indicate an invalid INTx IRQ.
* MSI interrupts allocate a block of interrupts starting at the end
* of the I/O APIC range. When running under the Xen Hypervisor, an
* additional range of IRQ values are available for binding to event
* channel events.
*/
#define MINIMUM_MSI_INT 256
extern u_int first_msi_irq;
extern u_int num_io_irqs;
extern u_int num_msi_irqs;

4
sys/x86/x86/msi.c
View File

@ -153,6 +153,8 @@ struct pic msi_pic = {
};
u_int first_msi_irq;
SYSCTL_UINT(_machdep, OID_AUTO, first_msi_irq, CTLFLAG_RD, &first_msi_irq, 0,
"Number of first IRQ reserved for MSI and MSI-X interrupts");
u_int num_msi_irqs = 512;
SYSCTL_UINT(_machdep, OID_AUTO, num_msi_irqs, CTLFLAG_RDTUN, &num_msi_irqs, 0,
@ -339,7 +341,7 @@ msi_init(void)
if (num_msi_irqs == 0)
return;
first_msi_irq = max(MINIMUM_MSI_INT, num_io_irqs);
first_msi_irq = num_io_irqs;
if (num_msi_irqs > UINT_MAX - first_msi_irq)
panic("num_msi_irq too high");
num_io_irqs = first_msi_irq + num_msi_irqs;

2
sys/x86/xen/pvcpu_enum.c
View File

@ -199,7 +199,7 @@ xenpv_setup_io(void)
* this is legacy code so just keep using the previous
* behaviour and assume a maximum of 256 interrupts.
*/
num_io_irqs = max(MINIMUM_MSI_INT - 1, num_io_irqs);
num_io_irqs = max(255, num_io_irqs);
acpi_SetDefaultIntrModel(ACPI_INTR_APIC);
}

2
sys/x86/xen/xen_msi.c
View File

@ -57,7 +57,7 @@ xen_msi_init(void)
{
MPASS(num_io_irqs > 0);
first_msi_irq = min(MINIMUM_MSI_INT, num_io_irqs);
first_msi_irq = num_io_irqs;
if (num_msi_irqs > UINT_MAX - first_msi_irq)
panic("num_msi_irq too high");
num_io_irqs = first_msi_irq + num_msi_irqs;