This is the mail archive of the
mailing list for the eCos project.
Re: Spurious interrupt on ARM.
- From: Nick Garnett <nickg at calivar dot com>
- To: Andrew Parlane <andrewp at carallon dot com>, ecos-discuss at ecos dot sourceware dot org
- Date: Fri, 01 Nov 2013 17:42:20 +0000
- Subject: Re: Spurious interrupt on ARM.
- Authentication-results: sourceware.org; auth=none
- References: <52729021 dot 3080205 at carallon dot com> <5273DFAE dot 1080000 at calivar dot com> <5273E2EE dot 3010908 at carallon dot com>
On 01/11/13 17:20, Andrew Parlane wrote:
> Sorry, I should have been a bit more clear.
> First we skip the ISR by jumping to the spurious_IRQ label, and then we
> switch stacks if necessary, then we have (line numbers may vary):
> 941 // The return value from the handler (in r0) will indicate
> whether a
> 942 // DSR is to be posted. Pass this together with a pointer to the
> 943 // interrupt object we have just used to the interrupt tidy
> up routine.
> 945 // don't run this for spurious interrupts!
> 946 cmp v1,#CYGNUM_HAL_INTERRUPT_NONE
> 947 beq 17f
> 948 ldr r1,.hal_interrupt_objects
> 949 ldr r1,[r1,v1,lsl #2]
> 950 mov r2,v6 // register frame
> 952 THUMB_MODE(r3,10)
> 954 bl interrupt_end // post any bottom layer handler
> 955 // threads and call scheduler
> 956 ARM_MODE(r1,10)
> 957 17:
> So it compares the result of hal_IRQ_handler (stored in v1) with
> CYGNUM_HAL_INTERRUPT_NONE, and jumps forwards to label 17: which is
> after interrupt_end. if it was a spurious IRQ.
Hmm. You're right. That is clearly wrong. Our own sources have the
following code, which is slightly different:
// The return value from the handler (in r0) will indicate
// DSR is to be posted. Pass this together with a pointer to the
// interrupt object we have just used to the interrupt tidy up
// For a spurious interrupt, pass a NULL object. interrupt_end()
// handle that and still unlock the scheduler.
ldr r1,[r1,v1,lsl #2]
mov r2,v6 // register frame
So interrupt_end does get called, but with a NULL interrupt object pointer.
Nick Garnett Kernel Architect
eCosCentric Limited http://www.eCosCentric.com The eCos experts
Barnwell House, Barnwell Drive, Cambridge, UK. Tel: +44 1223 245571
Registered in England and Wales: Reg No: 4422071
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss