RE: [ACPI] ACPI global lock macros

[Yu, Luming]

I have filed a tracker http://bugme.osdl.org/show_bug.cgi?id=1669  , And a proposal patch based on Paul's proposal filed there.
--Luming

-----Original Message-----
From: acpi-devel-admin@xxxxxxxxxxxxxxxxxxxxx [mailto:acpi-devel-admin@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Yu, Luming
Sent: 2003?12?11? 15:06
To: Paul Menage; agrover@xxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx; acpi-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [ACPI] ACPI global lock macros


>>#define ACPI_ACQUIRE_GLOBAL_LOCK(GLptr, Acq) \
>>     do { \
>>        asm volatile("1:movl   (%1),%%eax;" \
>>             "movl   %%eax,%%edx;" \
>>             "andl   %2,%%edx;" \
>>             "btsl   $0x1,%%edx;" \
>>             "adcl   $0x0,%%edx;" \
>>             "lock;  cmpxchgl %%edx,(%1);" \
>>             "jnz    1b;" \
>>             "cmpb   $0x3,%%dl;" \
>>             "sbbl   %0,%0" \
>>             :"=r"(Acq):"r"(GLptr),"i"(~1L):"dx", "ax"); \
>>     } while(0)

Above code have a bug! Considering below code:

u8	acquired = FALSE;

ACPI_ACQUIRE_GLOBAL_LOC(acpi_gbl_common_fACS.global_lock, acquired);
if(acquired) {
....
}

Gcc will complain " ERROR: '%cl' not allowed with sbbl ". And I think any other compiler will
complain that  too !

How about  below changes to your proposal code.

<             "sbbl   %0,%0" \
<             :"=r"(Acq):"r"(GLptr),"i"(~1L):"dx","ax"); \
---
>             "sbbl   %%eax,%%eax" \
>             :"=a"(Acq):"r"(GLptr),"i"(~1L):"dx"); \

PS. I'm very curious about how could you find this bug.  

Thanks
Luming



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