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Re: [RISC-V] [tech-fast-int] [RISC-V] [tech-privileged] Resumable NMI proposal
RNMI has separate exception vector from regular exceptions.
Krste
| Oops - I reread that - Paul is correct; nmcause is not modified. The handler has no guaranteed way of handling an exception.
| IT
RNMI has separate exception vector from regular exceptions.
Krste
| Oops - I reread that - Paul is correct; nmcause is not modified. The handler has no guaranteed way of handling an exception.
| IT
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By
Krste Asanovic
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#433
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Re: Resumable NMI proposal
| I would like a clarification on whether this replaces the existing NMI, or are you saying there are two different things, NMI and RNMI? I doubt it, but I wanted to check.
Enhances NMI by adding
| I would like a clarification on whether this replaces the existing NMI, or are you saying there are two different things, NMI and RNMI? I doubt it, but I wanted to check.
Enhances NMI by adding
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By
Krste Asanovic
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#432
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Re: Resumable NMI proposal
M-mode or HS-mode can always create equivalent for S-mode.
I don't believe hardware delegation makes sense for NMIs.
Krste
| I'd expect that S-mode software will also want to be able to receive
M-mode or HS-mode can always create equivalent for S-mode.
I don't believe hardware delegation makes sense for NMIs.
Krste
| I'd expect that S-mode software will also want to be able to receive
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By
Krste Asanovic
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#431
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Re: Resumable NMI proposal
| I'll jump in with a few more. :)
| From an architectural point of view, I don't like the fact that an NMI blocks further NMI until it leaves its handler. There may be NMIs that can save
| the state
| I'll jump in with a few more. :)
| From an architectural point of view, I don't like the fact that an NMI blocks further NMI until it leaves its handler. There may be NMIs that can save
| the state
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By
Krste Asanovic
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#430
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Re: Resumable NMI proposal
| Even though this is hot off the press, I'll jump in with a few small comments:
| - In mnstatus, shouldn't there also be a bit like the mstatus.MPV bit (for when the H extension is implemented and
| Even though this is hot off the press, I'll jump in with a few small comments:
| - In mnstatus, shouldn't there also be a bit like the mstatus.MPV bit (for when the H extension is implemented and
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By
Krste Asanovic
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#429
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Re: [RISC-V] [tech-fast-int] [RISC-V] [tech-privileged] Resumable NMI proposal
Oops - I reread that - Paul is correct; nmcause is not modified. The handler has no guaranteed way of handling an exception.
IT can leave breadcrumbs, but can't guarantee they will be correct
Oops - I reread that - Paul is correct; nmcause is not modified. The handler has no guaranteed way of handling an exception.
IT can leave breadcrumbs, but can't guarantee they will be correct
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By
Allen Baum
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#428
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Re: [RISC-V] [tech-fast-int] [RISC-V] [tech-privileged] Resumable NMI proposal
I am assuming here that NMI is an interrupt, not an exception. Both trap, but an mmie-bit only affects interrupts, not exceptions.
So, on entry, the handler knows if this was caused by an NMI or by an
I am assuming here that NMI is an interrupt, not an exception. Both trap, but an mmie-bit only affects interrupts, not exceptions.
So, on entry, the handler knows if this was caused by an NMI or by an
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By
Allen Baum
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#427
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Re: Resumable NMI proposal
"If the hart encounters an exception while the `rnmie` bit is clear, theexception state is written to `mepc` and `mcause`, `mstatus.mpp` is
set to M-mode, and the hart jumps to the RNMI exception
"If the hart encounters an exception while the `rnmie` bit is clear, theexception state is written to `mepc` and `mcause`, `mstatus.mpp` is
set to M-mode, and the hart jumps to the RNMI exception
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By
Paul Donahue
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#426
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Re: Resumable NMI proposal
I would like a clarification on whether this replaces the existing NMI, or are you saying there are two different things, NMI and RNMI? I doubt it, but I wanted to check.
I am concerned that the
I would like a clarification on whether this replaces the existing NMI, or are you saying there are two different things, NMI and RNMI? I doubt it, but I wanted to check.
I am concerned that the
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By
Earl Killian
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#425
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Re: Resumable NMI proposal
I'd expect that S-mode software will also want to be able to receive RNMIs, so it is probably worth thinking through how that would work at the same time.
Jonathan
I'd expect that S-mode software will also want to be able to receive RNMIs, so it is probably worth thinking through how that would work at the same time.
Jonathan
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By
Jonathan Behrens <behrensj@...>
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#424
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Re: Resumable NMI proposal
I'll jump in with a few more. :)
From an architectural point of view, I don't like the fact that an NMI blocks further NMI until it leaves its handler. There may be NMIs that can save the state they
I'll jump in with a few more. :)
From an architectural point of view, I don't like the fact that an NMI blocks further NMI until it leaves its handler. There may be NMIs that can save the state they
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By
Brian Grayson
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#423
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Re: Resumable NMI proposal
Even though this is hot off the press, I'll jump in with a few small comments:
- In mnstatus, shouldn't there also be a bit like the mstatus.MPV bit (for when the H extension is implemented and
Even though this is hot off the press, I'll jump in with a few small comments:
- In mnstatus, shouldn't there also be a bit like the mstatus.MPV bit (for when the H extension is implemented and
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By
Greg Favor
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#422
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Resumable NMI proposal
Current RISC-V specs only have a non-resumable NMI definition. The
following proposal would add resumable NMI support. This was one of
the features requested for priv 1.12 or RVA/RVM22.
This is up
Current RISC-V specs only have a non-resumable NMI definition. The
following proposal would add resumable NMI support. This was one of
the features requested for priv 1.12 or RVA/RVM22.
This is up
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By
Krste Asanovic
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#421
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Re: MPIE and MPP update when returning from interrupt with MRET
When an exception or an ECALL arrives at its handler, the privilege of the code running before the exception/ECALL is always available in MPP or SPP.
Bill
When an exception or an ECALL arrives at its handler, the privilege of the code running before the exception/ECALL is always available in MPP or SPP.
Bill
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By
Bill Huffman
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#420
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Re: MPIE and MPP update when returning from interrupt with MRET
This is in the priv spec sec 3.1.6.1 - just search for mret.
My explanation of why MPP reverts to Umode is to prevent privilege escalation if you go off the end of the 1-deep privilege level
This is in the priv spec sec 3.1.6.1 - just search for mret.
My explanation of why MPP reverts to Umode is to prevent privilege escalation if you go off the end of the 1-deep privilege level
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By
Allen Baum
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#419
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Re: MPIE and MPP update when returning from interrupt with MRET
privilege transitions from levels other than U to a handler at levels other than M are certainly possible.
*DELEG,*IE amd *EXCEPT will enable exception handler entry to non-M privilege moss
privilege transitions from levels other than U to a handler at levels other than M are certainly possible.
*DELEG,*IE amd *EXCEPT will enable exception handler entry to non-M privilege moss
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By
Richard Trauben
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#418
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MPIE and MPP update when returning from interrupt with MRET
Hello
The privileged architecture says that when returning from interrupt with MRET, MPIE is set to 1 (and MPP is set to U).
What is the rational behind ? Is it still in the context of supporting
Hello
The privileged architecture says that when returning from interrupt with MRET, MPIE is set to 1 (and MPP is set to U).
What is the rational behind ? Is it still in the context of supporting
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By
Anne MERLANDE
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#417
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ePMP update
Hi TEE group,
I would like to give a quick update on ePMP spec.
Public review
We are still waiting for unpriv group to approve new CSR address assignment. It’s been pending for a while because
Hi TEE group,
I would like to give a quick update on ePMP spec.
Public review
We are still waiting for unpriv group to approve new CSR address assignment. It’s been pending for a while because
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By
Joe Xie
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#416
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Re: [EXTERNAL]Re: [RISC-V] [tech-privileged] Performance Monitor Interrupts
Yes.
It's not fully in my control, but I'm hoping within the next week or two.
Greg
Yes.
It's not fully in my control, but I'm hoping within the next week or two.
Greg
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By
Greg Favor
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#415
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Re: [EXTERNAL]Re: [RISC-V] [tech-privileged] Performance Monitor Interrupts
(+platforms, which Mark had added in.)
Thanks for the quick reply Greg. Good to know it is of concern to others.😊
I assume the specification will be posted for public review in the
(+platforms, which Mark had added in.)
Thanks for the quick reply Greg. Good to know it is of concern to others.😊
I assume the specification will be posted for public review in the
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By
Sanjay Patel <spatel@...>
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#414
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