according to armv6-m/armv7-m arch reference manual:
the three ISB {<opt>}, DSB {<opt>}, DMB {<opt>} instructions <opt>
field are defined as:
Specifies an optional limitation on the ISB/DSB/DMB operation. Allowered
values are:
Full system ISB/DSB/DMB operation, encoded as option=='1111'. Can be
omitted.
All other encodings of the options are RESERVED.
the "#opt" field of "isb #opt"
So we could remove the options field in Armv7-m platform.
The following are the build error with greenhills compiler:
CC: common/arm_exit.c [asarm] (error #2071) /tmp/gh_001h70j1.si 92: bad parameter
isb 15
------^
[asarm] (error #2071) /tmp/gh_001h70j1.si 112: bad parameter
isb 15
------^
[asarm] (error) errors during processing
According to armv8-m arch reference manual:
the ISB/DMB instruction's "opt" encoding rule is same as
armv6-m/armv7-m, but the "DSB" instruction is different, in armv8-m, the
"DSB {<opt>}" field has two valid encoding options: 0b0000, 0b0100.
and all other encoding options are reserved.
In Armv7-a/Armv8-a, the dsb/dmb option field has 8 valid state value.
Signed-off-by: guoshichao <guoshichao@xiaomi.com>
693e869404