177 lines
5.3 KiB
Plaintext
177 lines
5.3 KiB
Plaintext
README
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======
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This README file describes the contents of the build configurations available
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for the NuttX QEMU i486 port.
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Contents
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========
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* QEMU
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- Building QEMU
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- Cygwin Build Problems
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- Running QEMU
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* Toolchains
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- Cygwin Buildroot Toolchain
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- Buildroot Instructions
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* FAQ
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* Configurations
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- ostest
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- nsh
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QEMU
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====
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QEMU is a generic and open source machine emulator and virtualizer. Here are
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some links (which will probably be mostly outdated by the time your read this):
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Home Page: http://wiki.qemu.org/Main_Page
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Downloads: http://wiki.qemu.org/Download
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Documentation: http://wiki.qemu.org/Manual
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Usage: qemu -nographic -kernel nuttx.elf
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Building QEMU
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-------------
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tar zxf qemu-0.14.0.tar.gz
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cd qemu-0.14.0
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./configure --target-list=i386-softmmu
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make
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make install
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Cygwin Build Problems
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---------------------
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Error:
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"gcc: The -mno-cygwin flag has been removed; use a mingw-targeted cross-compiler."
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Workaround:
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None known. It does not seem possible to build QEMU using the Cygwin gcc.
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I tried editing configure. Removing the following line will allow QEMU to
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configure:
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QEMU_CFLAGS="-mno-cygwin $QEMU_CFLAGS"
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However, it then fails later during the compilation phase.
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Recommendation:
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1. Google for "qemu windows download" and download some pre-built QEMU
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binaries. I found 0.14.0 here: http://dietpc.org/windows/qemu/, or
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2. Try building QEMU with MingGW (I understand that this is difficult).
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NOTE: As of this writing, I have not been successful getting ANY pre-built
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version of QEMU to work successfully with WinXP. The same binaries work
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fine on Vista, however.
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Running QEMU
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------------
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In the top-level NuttX directory:
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qemu -cpu 486 -m 2 -kernel nuttx.elf -nographic
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The -nographic option redirects COM1 to your console. However, the -nographic
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option does not work under Cygwin. For simple testing under Cygwin, I use
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qemu -cpu 486 -m 2 -kernel nuttx.elf -serial file:test.txt
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which will send COM1 output to the file test.txt.
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Toolchains
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==========
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Two target environments are supported: (1) Linux and (2) Cygwin under Windows.
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Any GCC toolchain that can produce i486 ELF binaries should work. On Linux,
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you can probably use the installed system gcc. But that will not work with
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Cygwin. Why? Because the Cygwin gcc (and probably the MinGW gcc as well) do
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not produce ELF final binaries but, rather, DOS MZ executables (i.e., .exe
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files). Those cannot be used with QEMU.
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NOTE: It has also been reported to me that with a certain Ubuntu virtual
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installation, the native x86 did not build correct i486 code. Other
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installations of the same vintage do not have such issues. However,
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there is always a possibility that any GCC release will be incompatible
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with i486. That fallback used by this person in this particular case
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was to use the Buildroot i486 cross-development tool described below. I
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suspect that this was not necessary, but it was a simple work-around
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that allowed that person to build a work-able system.
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In any event, the file */setenv.sh should be modified to point to the correct
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path to the GCC toolchain (if different from the default in your PATH
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variable).
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Cygwin Buildroot Toolchain
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--------------------------
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With Cygwin the solution is to build an i486 cross-development toolchain to
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generate the i486 ELF files needed by QEMU. The NuttX buildroot package will
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create such a toolchain.
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NOTE: As of this writing, none of the released buildroot packages support the
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i486 build. This is only available in GIT or in any any 1.10 or later buildroot
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release.
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Buildroot Instructions
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----------------------
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1. You must have already configured Nuttx in <some-dir>/nuttx.
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cd tools
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./configure.sh qemu-i486/<sub-dir>
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2. Download the latest buildroot package into <some-dir>
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3. unpack the buildroot tarball. The resulting directory may
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have versioning information on it like buildroot-x.y.z. If so,
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rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.
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4. cd <some-dir>/buildroot
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5. cp configs/i486-defconfig-4.3.3 .config
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6. make oldconfig
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7. make
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8. Edit setenv.h, if necessary, so that the PATH variable includes
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the path to the newly built binaries.
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See the file configs/README.txt in the buildroot source tree. That has more
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detailed PLUS some special instructions that you will need to follow if you
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run into problems building the toolchain for Cygwin under Windows.
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FAQ
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===
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Q: I get the following error message, "undefined reference to '__stack_chk_fail'"
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A: Add -fno-stack-protector to ARCHCPUFLAGS in you Make.defs file. Switch the
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commenting on the following two lines in the Make.defs file:
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ARCHCPUFLAGS = -march=i486 -mtune=i486 -fno-builtin
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#ARCHCPUFLAGS = -march=i486 -mtune=i486 -fno-builtin -fno-stack-protector
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Configurations
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==============
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ostest
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------
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The "standard" NuttX examples/ostest configuration. This
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configuration may be selected as follows:
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cd <nuttx-directory>/tools
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./configure.sh qemu-i486/ostest
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nsh
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---
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Configures the NuttShell (nsh) located at examples/nsh. This
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configuration may be selected as follows:
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cd <nuttx-directory>/tools
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./configure.sh qemu-i486/nsh
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