Re: Question about mip and vsip


Greg Favor
 

On Sat, Nov 26, 2022 at 8:41 PM jupposcar <jupposcar@...> wrote:
1. You said : “Priv section 9.4.3 defines these bits as aliases (of bits in hip), so yes - M-mode software can modify these bits.” 
But I don’t know they are read-only aliases ? or read-write aliases ? In other word, Can the CSR instruction  with the CSR number 0x344 (mip) modify these bits?

Per Priv section 2.2, 0x344 is read/write.  And hip is also read-write.  So the mip aliases of these hip bits are also read/write in mip.
 
Or only CSR instruction with the CSR number 0x644 (hip) can modify these bits?

2. The ISA said : “If implemented, SEIP is read-only in sip."(Priv section 4.3.1)
It means sip.SEIP is read-only for S-mode. Similarly, is vsip.SEIP read-only for VS-mode ?

First, I think you mean section 5.1.3 in the latest draft of the Priv spec.  And yes, you're correct.
 
Greg

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