Messages in this thread | | | Subject | RE: Updated MSI Patches | Date | Tue, 12 Aug 2003 10:04:34 -0700 | From | "Nguyen, Tom L" <> |
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> diff -X excludes -urN linux-2.6.0-test2/arch/i386/kernel/io_apic.c linux-2.6.0-test2-create-vectorbase/arch/i386/kernel/io_apic.c > --- linux-2.6.0-test2/arch/i386/kernel/io_apic.c 2003-07-27 13:00:21.000000000 -0400 > +++ linux-2.6.0-test2-create-vectorbase/arch/i386/kernel/io_apic.c 2003-08-05 09:25:54.000000000 -0400 > @@ -76,6 +76,20 @@ > int apic, pin, next; > } irq_2_pin[PIN_MAP_SIZE]; > > +#ifdef CONFIG_PCI_USE_VECTOR > +int vector_irq[NR_IRQS] = { [0 ... NR_IRQS -1] = -1}; > + > +static int platform_irq(int irq) > +{ > + if (platform_legacy_irq(irq)) > + return irq; > + else > + return vector_irq[irq]; > +} > +#else > +#define platform_irq(irq) (irq) > +#endif
> I wish you wouldn't mix up vector and irq like this :( This is really > beginning to look like IPF. When is an irq an irq and when is a vector a > vector? This can get very confusing very quickly. I spent a fair > amount of time debugging this last time due to the confusion in the > common_interrupt -> do_IRQ path, i'd hate for this to be a permanent > fixture. If you're going to change things just change everything > (including variable names) instead of making it conditional. I understand that mixing up vector and irq is very confusing. However, to support non-PCI legacy devices with IRQ less than 16, such as keyboard and mouse for example, may be impossilbe to achieve without mixing up. Some existing driver of legacy keyboard/mouse devices, for example, may use fixed IO ranges and fixed IRQs (as assigned to 1 for keyboard and 12 for mouse). If these device drivers use these fixed legacy IRQs and the interrupt routings for these non-PCI legacy devices use vectors, then the system may break. As you know, MSI support requires vector allocation instead of IRQ allocation since MSI does not require a support of BIOS IRQ table. Mixing vector with IRQ to be compatible with non-PCI legacy devices must be achieved. Last time, your suggestion of changing variable name from irq to vector is the good approach. I am looking at restructuring the code of the vector-base patch. I will send you an update when I am done for your feedback.
> diff -X excludes -urN linux-2.6.0-test2-create-vectorbase/arch/i386/kernel/io_apic.c linux-2.6.0-test2-create-msi/arch/i386/kernel/io_apic.c > --- linux-2.6.0-test2-create-vectorbase/arch/i386/kernel/io_apic.c 2003-08-05 09:25:54.000000000 -0400 > +++ linux-2.6.0-test2-create-msi/arch/i386/kernel/io_apic.c 2003-08-05 09:45:25.000000000 -0400 > @@ -427,6 +427,11 @@ > /* Is this an active IRQ? */ > if (!irq_desc[j].action) > continue; > +#ifdef CONFIG_PCI_MSI > + /* Is this an active MSI? */ > + if (msi_desc[j]) > + continue; > +#endif
> Is there any locking for msi_desc? Or are you relying on something else? Since the code determinces whether this entry is NULL or not, I think any locking for msi_desc may not be required.
> + if (current_vector == FIRST_SYSTEM_VECTOR) > + panic("ran out of interrupt sources!");
> Please just fail and return -ENOSPC or something like that. Good. Thanks!
Thanks, Long
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