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Replace TIP admonition with NOTE. (#1549)
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Replaces the TIP admonition with NOTE.
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wmat authored Jul 19, 2024
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8 changes: 4 additions & 4 deletions src/c-st-ext.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,7 @@ and/or D) is also implemented. In addition, RV32C includes a compressed
jump and link instruction to compress short-range subroutine calls,
where the same opcode is used to compress ADDIW for RV64C and RV128C.

[TIP]
[NOTE]
====
Double-precision loads and stores are a significant fraction of static
and dynamic instructions, hence the motivation to include them in the
Expand Down Expand Up @@ -100,7 +100,7 @@ instructions in one C instruction.
It is important to note that the C extension is not designed to be a
stand-alone ISA, and is meant to be used alongside a base ISA.

[TIP]
[NOTE]
====
Variable-length instruction sets have long been used to improve code
density. For example, the IBM Stretch cite:[stretch], developed in the late 1950s, had
Expand Down Expand Up @@ -526,7 +526,7 @@ latexmath:[$\textit{rs1}{\neq}\texttt{x0}$]; the code point with
latexmath:[$\textit{rs1}{=}\texttt{x0}$] corresponds to the C.EBREAK
instruction.

[TIP]
[NOTE]
====
Strictly speaking, C.JALR does not expand exactly to a base RVI
instruction as the value added to the PC to form the link address is 2
Expand Down Expand Up @@ -707,7 +707,7 @@ C.MV copies the value in register _rs2_ into register _rd_. C.MV expands
into `add rd, x0, rs2`. C.MV is only valid when
`rs2≠x0` the code points with `rs2=x0` correspond to the C.JR instruction. The code points with `rs2≠x0` and `rd=x0` are HINTs.

[TIP]
[NOTE]
====
_C.MV expands to a different instruction than the canonical MV
pseudoinstruction, which instead uses ADDI. Implementations that handle
Expand Down
18 changes: 9 additions & 9 deletions src/counters.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ counters (CYCLE, TIME, and INSTRET), which have dedicated functions
(cycle count, real-time clock, and instructions retired, respectively).
The Zicntr extension depends on the Zicsr extension.

[TIP]
[NOTE]
====
We recommend provision of these basic counters in implementations as
they are essential for basic performance analysis, adaptive and dynamic
Expand All @@ -35,7 +35,7 @@ the full 64-bit CSRs directly. In particular, the RDCYCLE, RDTIME, and
RDINSTRET pseudoinstructions read the full 64 bits of the `cycle`,
`time`, and `instret` counters.

[TIP]
[NOTE]
====
The counter pseudoinstructions are mapped to the read-only
`csrrs rd, counter, x0` canonical form, but the other read-only CSR
Expand All @@ -47,7 +47,7 @@ For base ISAs with XLEN=32, the Zicntr extension enables the three
RDTIME, and RDINSTRET pseudoinstructions provide the lower 32 bits, and
the RDCYCLEH, RDTIMEH, and RDINSTRETH pseudoinstructions provide the
upper 32 bits of the respective counters.
[TIP]
[NOTE]
====
We required the counters be 64 bits wide, even when XLEN=32, as
otherwise it is very difficult for software to determine if values have
Expand All @@ -67,7 +67,7 @@ overflow in practice. The rate at which the cycle counter advances will
depend on the implementation and operating environment. The execution
environment should provide a means to determine the current rate
(cycles/second) at which the cycle counter is incrementing.
[TIP]
[NOTE]
====
RDCYCLE is intended to return the number of cycles executed by the
processor core, not the hart. Precisely defining what is a "core" is
Expand Down Expand Up @@ -128,7 +128,7 @@ should be constant within a small error bound. The environment should
provide a means to determine the accuracy of the clock (i.e., the
maximum relative error between the nominal and actual real-time clock
periods).
[TIP]
[NOTE]
====
On some simple platforms, cycle count might represent a valid
implementation of RDTIME, in which case RDTIME and RDCYCLE may return
Expand All @@ -141,7 +141,7 @@ bound should be set based on the requirements of the platform.

The real-time clocks of all harts must be synchronized to within one
tick of the real-time clock.
[TIP]
[NOTE]
====
As with other architectural mandates, it suffices to appear "as if"
harts are synchronized to within one tick of the real-time clock, i.e.,
Expand All @@ -154,7 +154,7 @@ hart from some arbitrary start point in the past. RDINSTRETH is only
present when XLEN=32 and reads bits 63-32 of the same instruction
counter. The underlying 64-bit counter should never overflow in
practice.
[TIP]
[NOTE]
====
Instructions that cause synchronous exceptions, including ECALL and
EBREAK, are not considered to retire and hence do not increment the
Expand All @@ -180,7 +180,7 @@ hardware performance counters, `hpmcounter3-hpmcounter31`. When
XLEN=32, the upper 32 bits of these performance counters are accessible
via additional CSRs `hpmcounter3h- hpmcounter31h`. The Zihpm extension
depends on the Zicsr extension.
[TIP]
[NOTE]
====
In some applications, it is important to be able to read multiple
counters at the same instant in time. When run under a multitasking
Expand All @@ -202,7 +202,7 @@ exception or may return a constant value.
The execution environment should provide a means to determine the number
and width of the implemented counters, and an interface to configure the
events to be counted by each counter.
[TIP]
[NOTE]
====
For execution environments implemented on RISC-V privileged platforms,
the privileged architecture manual describes privileged CSRs controlling
Expand Down
4 changes: 2 additions & 2 deletions src/d-st-ext.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ so, the _n_ least-significant bits of the input are used as
the input value, otherwise the input value is treated as an
_n_-bit canonical NaN.

[TIP]
[NOTE]
====
Earlier versions of this document did not define the behavior of feeding
the results of narrower or wider operands into an operation, except to
Expand Down Expand Up @@ -184,7 +184,7 @@ include::images/wavedrom/d-xwwx.adoc[]
[[fmvxddx]]
//.Double-precision float move to _rd_

[TIP]
[NOTE]
====
Early versions of the RISC-V ISA had additional instructions to allow
RV32 systems to transfer between the upper and lower portions of a
Expand Down
6 changes: 3 additions & 3 deletions src/f-st-ext.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ instructions operate on values in the floating-point register file.
Floating-point load and store instructions transfer floating-point
values between registers and memory. Instructions to transfer values to and from the integer register file are also provided.

[TIP]
[NOTE]
====
We considered a unified register file for both integer and
floating-point values as this simplifies software register allocation
Expand Down Expand Up @@ -189,7 +189,7 @@ quiet bit. For single-precision floating-point, this corresponds to the pattern
(((NaN, generation)))
(((NaN, propagation)))

[TIP]
[NOTE]
====
We considered propagating NaN payloads, as is recommended by the
standard, but this decision would have increased hardware cost.
Expand Down Expand Up @@ -432,7 +432,7 @@ include::images/wavedrom/spfloat-mv.adoc[]
[[spfloat-mv]]
//.SP floating point move

[TIP]
[NOTE]
====
The base floating-point ISA was defined so as to allow implementations
to employ an internal recoding of the floating-point format in registers to simplify handling of subnormal values and possibly to reduce functional unit latency. To this end, the F extension avoids
Expand Down
16 changes: 8 additions & 8 deletions src/intro.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@ efficiency.
* An ISA that simplifies experiments with new privileged architecture
designs.
[TIP]
[NOTE]
====
Commentary on our design decisions is formatted as in this paragraph.
This non-normative text can be skipped if the reader is only interested
Expand Down Expand Up @@ -64,7 +64,7 @@ volume provides the design of the first ("classic") privileged
architecture. The manuals use IEC 80000-13:2008 conventions, with a byte
of 8 bits.

[TIP]
[NOTE]
====
In the unprivileged ISA design, we tried to remove any dependence on
particular microarchitectural features, such as cache line size, or on
Expand Down Expand Up @@ -144,7 +144,7 @@ environments for guest operating systems.
harts on an underlying x86 system, and which can provide either a
user-level or a supervisor-level execution environment.

[TIP]
[NOTE]
====
A bare hardware platform can be considered to define an EEI, where the
accessible harts, memory, and other devices populate the environment,
Expand Down Expand Up @@ -176,7 +176,7 @@ constitute forward progress:
* Any other event defined by an extension to constitute forward
progress.

[TIP]
[NOTE]
====
The term hart was introduced in the work on Lithe cite:[lithe-pan-hotpar09] and cite:[lithe-pan-pldi10] to provide a term to
represent an abstract execution resource as opposed to a software thread
Expand Down Expand Up @@ -230,7 +230,7 @@ base integer instruction set supporting a flat 128-bit address space
representation for signed integer values.


[TIP]
[NOTE]
====
Although 64-bit address spaces are a requirement for larger systems, we
believe 32-bit address spaces will remain adequate for many embedded and
Expand Down Expand Up @@ -382,7 +382,7 @@ harts may be entirely the same, or entirely different, or may be partly
different but sharing some subset of resources, mapped into the same or
different address ranges.

[TIP]
[NOTE]
====
For a purely "bare metal" environment, all harts may see an identical
address space, accessed entirely by physical addresses. However, when
Expand Down Expand Up @@ -552,7 +552,7 @@ instructions. These instructions are considered to be of minimal length:
bits. The encoding with bits [ILEN-1:0] all ones is also illegal; this
instruction is considered to be ILEN bits long.

[TIP]
[NOTE]
====
We consider it a feature that any length of instruction containing all
zero bits is not legal, as this quickly traps erroneous jumps into
Expand Down Expand Up @@ -587,7 +587,7 @@ instruction specification.
(((bi-endian)))
(((endian, bi-)))

[TIP]
[NOTE]
====
We originally chose little-endian byte ordering for the RISC-V memory
system because little-endian systems are currently dominant commercially
Expand Down
4 changes: 2 additions & 2 deletions src/m-st-ext.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ This chapter describes the standard integer multiplication and division
instruction extension, which is named "M" and contains instructions
that multiply or divide values held in two integer registers.

[TIP]
[NOTE]
====
We separate integer multiply and divide out from the base to simplify
low-end implementations, or for applications where integer multiply and
Expand Down Expand Up @@ -113,7 +113,7 @@ latexmath:[$-1$] |latexmath:[$2^{L}-1$] +
//|Overflow (signed only) |latexmath:[$-2^{L-1}$] |latexmath:[$-1$] |– |– |latexmath:[$-2^{L-1}$] |0
//|===

[TIP]
[NOTE]
====
We considered raising exceptions on integer divide by zero, with these
exceptions causing a trap in most execution environments. However, this
Expand Down
2 changes: 1 addition & 1 deletion src/rv128.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ flat 128-bit address space. The variant is a straightforward
extrapolation of the existing RV32I and RV64I designs.
(((RV128, design)))

[TIP]
[NOTE]
====
The primary reason to extend integer register width is to support larger
address spaces. It is not clear when a flat address space larger than 64
Expand Down
18 changes: 9 additions & 9 deletions src/rv32.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@

This chapter describes the RV32I base integer instruction set.

[TIP]
[NOTE]
====
RV32I was designed to be sufficient to form a compiler target and to
support modern operating system environments. The ISA was also designed
Expand Down Expand Up @@ -258,7 +258,7 @@ destination is register _rd_ for both register-immediate and
register-register instructions. No integer computational instructions
cause arithmetic exceptions.

[TIP]
[NOTE]
====
We did not include special instruction-set support for overflow checks
on integer arithmetic operations in the base instruction set, as many
Expand Down Expand Up @@ -581,7 +581,7 @@ a conditional branch instruction with an always-true condition. RISC-V
jumps are also PC-relative and support a much wider offset range than
branches, and will not pollute conditional-branch prediction tables.

[TIP]
[NOTE]
====
The conditional branches were designed to include arithmetic comparison
operations between two registers (as also done in PA-RISC, Xtensa, and
Expand Down Expand Up @@ -666,7 +666,7 @@ even though the load value is discarded.
The EEI will define whether the memory system is little-endian or
big-endian. In RISC-V, endianness is byte-address invariant.

[TIP]
[NOTE]
====
In a system for which endianness is byte-address invariant, the
following property holds: if a byte is stored to memory at some address
Expand Down Expand Up @@ -731,7 +731,7 @@ by address misalignment result in a contained trap (allowing software
running inside the execution environment to handle the trap) or a fatal
trap (terminating execution).

[TIP]
[NOTE]
====
Misaligned accesses are occasionally required when porting legacy code,
and help performance on applications when using any form of packed-SIMD
Expand Down Expand Up @@ -853,7 +853,7 @@ Base implementations shall treat all such reserved configurations as
normal fences with _fm_=0000, and standard software shall use only
non-reserved configurations.

[TIP]
[NOTE]
====
We chose a relaxed memory model to allow high performance from simple
machine implementations and from likely future coprocessor or
Expand All @@ -875,7 +875,7 @@ described in <<csrinsts>>, and the base
unprivileged instructions are described in the following section.


[TIP]
[NOTE]
====
The SYSTEM instructions are defined to allow simpler implementations to
always trap to a single software trap handler. More sophisticated
Expand Down Expand Up @@ -906,7 +906,7 @@ to reflect that they can be used more generally than to call a
supervisor-level operating system or debugger.
====

[TIP]
[NOTE]
====
EBREAK was primarily designed to be used by a debugger to cause
execution to stop and fall back into the debugger. EBREAK is also used
Expand Down Expand Up @@ -986,7 +986,7 @@ HINT space is reserved for standard HINTs. The remainder of the HINT
space is designated for custom HINTs: no standard HINTs will ever be
defined in this subspace.

[TIP]
[NOTE]
====
We anticipate standard hints to eventually include memory-system spatial
and temporal locality hints, branch prediction hints, thread-scheduling
Expand Down
2 changes: 1 addition & 1 deletion src/rv32e.adoc
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ RV64I are also compatible with RV32E and RV64E, respectively.
RV32E and RV64E reduce the integer register count to 16 general-purpose
registers, (`x0-x15`), where `x0` is a dedicated zero register.

[TIP]
[NOTE]
====
We have found that in the small RV32I core implementations, the upper 16
registers consume around one quarter of the total area of the core
Expand Down
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