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Merge pull request #522 from staroselskii/patch-4

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interrupts-10.md: a couple more typos
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0xAX 2017-09-17 00:09:05 +06:00 committed by GitHub
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interrupts/interrupts-10.md
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@ -284,7 +284,7 @@ if (retval)
return retval;
```
Note that the call of the `__setup_irq` function is placed between the `chip_bus_lock` and the `chip_bus_sync_unlock` functions. These functions locl/unlock access to slow bus (like [i2c](https://en.wikipedia.org/wiki/I%C2%B2C)) chips. Now let's look at the implementation of the `__setup_irq` function. In the beginning of the `__setup_irq` function we can see a couple of different checks. First of all we check that the given interrupt descriptor is not `NULL`, `irqchip` is not `NULL` and that given interrupt descriptor module owner is not `NULL`. After this we check is interrupt nest into another interrupt thread or not, and if it is nested we replace the `irq_default_primary_handler` with the `irq_nested_primary_handler`.
Note that the call of the `__setup_irq` function is placed between the `chip_bus_lock` and the `chip_bus_sync_unlock` functions. These functions lock/unlock access to slow busses (like [i2c](https://en.wikipedia.org/wiki/I%C2%B2C)) chips. Now let's look at the implementation of the `__setup_irq` function. In the beginning of the `__setup_irq` function we can see a couple of different checks. First of all we check that the given interrupt descriptor is not `NULL`, `irqchip` is not `NULL` and that given interrupt descriptor module owner is not `NULL`. After this we check if the interrupt is nested into another interrupt thread or not, and if it is nested we replace the `irq_default_primary_handler` with the `irq_nested_primary_handler`.
In the next step we create an irq handler thread with the `kthread_create` function, if the given interrupt is not nested and the `thread_fn` is not `NULL`:
@ -316,7 +316,7 @@ Here we iterate over all the cleared bit of the `used_vectors` bitmap starting a
int first_system_vector = FIRST_SYSTEM_VECTOR; // 0xef
```
and set interrupt gates with the `i` vector number and the `irq_entries_start + 8 * (i - FIRST_EXTERNAL_VECTOR)` start address. Only one things is unclear here - the `irq_entries_start`. This symbol defined in the [arch/x86/entry/entry_64.S](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/arch/x86/entry_entry_64.S) assembly file and provides `irq` entries. Let's look at it:
and set interrupt gates with the `i` vector number and the `irq_entries_start + 8 * (i - FIRST_EXTERNAL_VECTOR)` start address. Only one thing is unclear here - the `irq_entries_start`. This symbol defined in the [arch/x86/entry/entry_64.S](https://github.com/torvalds/linux/blob/16f73eb02d7e1765ccab3d2018e0bd98eb93d973/arch/x86/entry_entry_64.S) assembly file and provides `irq` entries. Let's look at it:
```assembly
.align 8