Files
gem5/src/arch/arm/ArmSemihosting.py
Andreas Sandberg a6be3fd503 arch-arm, dev-arm: Consistently use ISO prefixes
We currently use the traditional SI-like prefixes to represent
binary multipliers in some contexts. This is ambiguous in many cases
since they overload the meaning of the SI prefix.

Here are some examples of commonly used in the industry:
  * Storage vendors define 1 MB as 10**6 bytes
  * Memory vendors define 1 MB as 2**20 bytes
  * Network equipment treats 1Mbit/s as 10**6 bits/s
  * Memory vendors define 1Mbit as 2**20 bits

In practice, this means that a FLASH chip on a storage bus uses
decimal prefixes, but that same flash chip on a memory bus uses binary
prefixes. It would also be reasonable to assume that the contents of a
1Mbit FLASH chip would take 0.1s to transfer over a 10Mbit Ethernet
link. That's however not the case due to different meanings of the
prefix.

The quantity 2MX is treated differently by gem5 depending on the unit
X:

  * Physical quantities (s, Hz, V, A, J, K, C, F) use decimal prefixes.
  * Interconnect and NoC bandwidths (B/s) use binary prefixes.
  * Network bandwidths (bps) use decimal prefixes.
  * Memory sizes and storage sizes (B) use binary prefixes.

Mitigate this ambiguity by consistently using the ISO/IEC/SI prefixes
for binary multipliers for parameters and comments where appropriate.

Change-Id: I9b47194d26d71c8ebedda6c31a5bac54b600d3bf
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39575
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2021-01-24 18:44:21 +00:00

63 lines
3.1 KiB
Python

# Copyright (c) 2018, 2019 ARM Limited
# All rights reserved.
#
# The license below extends only to copyright in the software and shall
# not be construed as granting a license to any other intellectual
# property including but not limited to intellectual property relating
# to a hardware implementation of the functionality of the software
# licensed hereunder. You may use the software subject to the license
# terms below provided that you ensure that this notice is replicated
# unmodified and in its entirety in all distributions of the software,
# modified or unmodified, in source code or in binary form.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer;
# redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution;
# neither the name of the copyright holders nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
from m5.params import *
from m5.SimObject import *
from m5.objects.Serial import SerialDevice
from m5.objects.Terminal import Terminal
class ArmSemihosting(SimObject):
type = 'ArmSemihosting'
cxx_header = "arch/arm/semihosting.hh"
cmd_line = Param.String("", "Command line to report to guest");
stdin = Param.String("stdin",
"Standard input (stdin for gem5's terminal)")
stdout = Param.String("stdout",
"Standard output (stdout for gem5's terminal)")
stderr = Param.String("stderr",
"Standard error (stderr for gem5's terminal)")
files_root_dir = Param.String("",
"Host root directory for files handled by Semihosting")
mem_reserve = Param.MemorySize("32MiB",
"Amount of memory to reserve at the start of the address map. This "
"memory won't be used by the heap reported to an application.");
stack_size = Param.MemorySize("32MiB", "Application stack size");
time = Param.Time('01/01/2009',
"System time to use ('Now' for actual time)")