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PeakRDL-BusDecoder/docs/dev_notes/Validation Needed

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Things that need validation by the compiler
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Many of these are probably already covered, but being paranoid.
Make a list of things as I think of them.
Keep them here in case I forget and re-think of them.
Mark these as follows:
X = Yes, confirmed that the compiler covers this
! = No! Confirmed that the compiler does not check this, and should.
? = TBD
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X resetsignal width
reset signals shall have width of 1
X Field has no knowable value
- does not implement storage
- hw is not writable
- sw is readable
- No reset value specified
--> emit a warning?
X References to a component or component property must use unambiguous array indexing
For example, if "array_o_regs" is an array...
The following is illegal:
my_reg.my_field->next = array_o_regs.thing
my_reg.my_field->next = array_o_regs.thing->anded
This is ok:
my_reg.my_field->next = array_o_regs[2].thing
my_reg.my_field->next = array_o_regs[2].thing->anded
NEVERMIND - compiler does not allow indefinite array references at all!
References are guaranteed to be unambiguous:
"Incompatible number of index dimensions after 'CTRL'. Expected 1, found 0."
X Clause 10.6.1-f (wide registers cannot have access side-effects)
X multiple field_reset in the same hierarchy
there can only be one signal declared with field_reset
in a given hierarchy
X multiple cpuif_reset in the same hierarchy
there can only be one signal declared with cpuif_reset
in a given hierarchy
X Mutually-exclusive property checking
--> Yes. compiler now auto-clears mutex partners on assign, so it is
implicitly handled
X incrwidth/incrvalue & decrvalue/decrwidth
these pairs are mutually exclusive.
Make sure they are not both set after elaboration
Compiler checks for mutex within the same scope, but
i dont think I check for mutexes post-elaborate
... or, make these properties clear each-other on assignment
X Illegal property references:
- reference any of the counter property references to something that isn't a counter
decrsaturate / incrsaturate / saturate
overflow / underflow
- reference hwclr or hwset, but the owner node has them set to False
means that the actual inferred signal doesnt exist!
- reference swwe/swwel or we/wel, but the owner node has them, AND their complement set to False
means that the actual inferred signal doesnt exist!
- only valid to reference if owner has this prop set
enable/mask
haltenable/haltmask
hwenable
hwmask
decr/incr, decr../incrthreshold/..value
- others references that may not always make sense:
intr/halt - target must contain interrupt/halt fields
next
is this ever illegal?
X If a node ispresent=true, and any of its properties are a reference,
then those references' ispresent shall also be true
This is an explicit clause in the spec: 5.3.1-i
X Flag illegal sw actions if not readable/writable
The following combinations dont get flagged currently:
sw=w; rclr;
sw=w; rset;
sw=r; woset;
sw=r; woclr;
their counterparts do get flagged. such as:
sw=w; onread=rclr;
X Signals marked as field_reset or cpuif_reset need to have activehigh/activelow
specified. (8.2.1-d states that activehigh/low does not have an implied default state if unset!)
Also applies to signals referenced by resetsignal
X incrvalue/decrvalue needs to be the same or narrower than counter itself
X field shall be hw writable if "next" is assigned.
X sticky=true + "(posedge|negedge|bothedge) intr"
Edge-sensitivty doesnt make sense for full-field stickiness
X we/wel + implied or explicit "sticky"/"stickybit"
we/wel modifier doesn't make sense here.
X sticky/stickybit shall be hw writable
X Illegal to use enable/mask/haltenable/haltmask on non-intr fields
X incrwidth/decrwidth must be between 1 and the width of the counter
X counter field that saturates should not set overflow
counter; incrsaturate; overflow;
counter; decrsaturate; underflow;
Flag this as an error on the overflow/underflow property.
overflow/underflow property is meaningless since it can never happen.
Same goes to prop references to overflow/underflow
! hwclr/hwset/we/wel probably shouldn't be able to reference itself
y->hwclr = y;
y->we = y;
... it works, but should it be allowed? Seems like user-error
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Things that need validation by this exporter
================================================================================
List of stuff in case I forget.
X = Yes! I already implemented this.
! = No! exporter does not enforce this yet
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X Contents of target are all internal. No external regs
X Does not contain any mem components
X Warn/error on any signal with cpuif_reset set, that is not in the top-level
addrmap. At the very least, warn that it will be ignored
X "bridge" addrmap not supported
export shall refuse to process an addrmap marked as a "bridge"
Only need to check top-level. Compiler will enforce that child nodes arent bridges
X regwidth/accesswidth is sane
X accesswidth == regwidth
Enforce this for now. Dont feel like supporting fancy modes yet
X regwidth < accesswidth
This is illegal and is enforced by the compiler.
X regwidth > accesswidth
Need to extend address decode strobes to have multiple bits
this is where looking at endianness matters to determine field placement
Dont feel like supporting this yet
X constant regwidth?
For now, probably limit to only allow the same regwidth everywhere?
X Do not allow unaligned addresses
All offsets & strides shall be a multiple of the regwidth used
X each reg needs to be aligned to its width
X each regfile/addrmap/stride shall be aligned to the largest regwidth it encloses
X Error if a property is a reference to something that is external, or enclosed
in an external component.
Limit this check to child nodes inside the export hierarchy
! async data signals
Only supporting async signals if they are exclusively used in resets.
Anything else declared as "async" shall emit a warning that it is ignored
I have zero interest in implementing resynchronizers
! Error if a property references a non-signal component, or property reference from
outside the export hierarchy
! Add warning for sticky race condition
stickybit and other similar situations generally should use hw precedence.
Emit a warning as appropriate
Or should this be a compiler warning??