doc: update and fix Qemu MIPS documentation

Update description to use the MIPS Malta board for Qemu.

Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>

1 files changed, 78 insertions, 195 deletions

diff --git a/doc/board/emulation/qemu-mips.rst b/doc/board/emulation/qemu-mips.rst
index d359251..5fd8a0a 100644
--- a/doc/board/emulation/qemu-mips.rst
+++ b/doc/board/emulation/qemu-mips.rst
@@ -1,246 +1,129 @@
 .. SPDX-License-Identifier: GPL-2.0+
-.. sectionauthor:: Vlad Lungu <vlad.lungu@windriver.com>
+.. sectionauthor:: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
 
 QEMU MIPS
 =========
 
-Qemu is a full system emulator. See http://www.nongnu.org/qemu/
+Qemu for MIPS is based on the MIPS Malta board. The built Malta U-Boot
+images can be used for Qemu and on physical hardware. The Malta board
+supports all combinations of Little and Big Endian as well as 32 bit
+and 64 bit.
 
 Limitations & comments
 ----------------------
-Supports the "-M mips" configuration of qemu: serial,NE2000,IDE.
-Supports little and big endian as well as 32 bit and 64 bit.
-Derived from au1x00 with a lot of things cut out.
-
-Supports emulated flash (patch Jean-Christophe PLAGNIOL-VILLARD) with
-recent qemu versions. When using emulated flash, launch with
--pflash <filename> and erase mips_bios.bin.
-
-
-Notes for the Qemu MIPS port
-----------------------------
+The memory size for Qemu is hard-coded to 256 MiB. For Malta Little Endian
+targets an extra endianness swapped image named *u-boot-swap.bin* is
+generated and required for Qemu.
 
 Example usage
-^^^^^^^^^^^^^
-
-Using u-boot.bin as ROM (replaces Qemu monitor):
+-------------
 
-32 bit, big endian
+Build for 32 bit, big endian:
 
 .. code-block:: bash
 
-   make qemu_mips_defconfig
-   qemu-system-mips -M mips -bios u-boot.bin -nographic
+  make malta_defconfig
+  make
+  UBOOT_BIN=u-boot.bin
+  QEMU_BIN=qemu-system-mips
+  QEMU_CPU=24Kc
 
-32 bit, little endian
+Build for 32 bit, little endian:
 
 .. code-block:: bash
 
-   make qemu_mipsel_defconfig
-   qemu-system-mipsel -M mips -bios u-boot.bin -nographic
+  make maltael_defconfig
+  make
+  UBOOT_BIN=u-boot-swap.bin
+  QEMU_BIN=qemu-system-mipsel
+  QEMU_CPU=24Kc
 
-64 bit, big endian
+Build for 64 bit, big endian:
 
 .. code-block:: bash
 
-   make qemu_mips64_defconfig
-   qemu-system-mips64 -cpu MIPS64R2-generic -M mips -bios u-boot.bin -nographic
+  make malta64_defconfig
+  make
+  UBOOT_BIN=u-boot.bin
+  QEMU_BIN=qemu-system-mips64
+  QEMU_CPU=MIPS64R2-generic
 
-64 bit, little endian
+Build for 64 bit, little endian:
 
 .. code-block:: bash
 
-   make qemu_mips64el_defconfig
-   qemu-system-mips64el -cpu MIPS64R2-generic -M mips -bios u-boot.bin -nographic
+  make malta64el_defconfig
+  make
+  UBOOT_BIN=u-boot-swap.bin
+  QEMU_BIN=qemu-system-mips64el
+  QEMU_CPU=MIPS64R2-generic
 
-or using u-boot.bin from emulated flash:
-
-if you use a QEMU version after commit 4224
+Generate NOR flash image with U-Boot binary:
 
 .. code-block:: bash
 
-   # create image:
-   dd of=flash bs=1k count=4k if=/dev/zero
-   dd of=flash bs=1k conv=notrunc if=u-boot.bin
-   # start it (see above):
-   qemu-system-mips[64][el] [-cpu MIPS64R2-generic] -M mips -pflash flash -nographic
-
-Download kernel + initrd
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-On ftp://ftp.denx.de/pub/contrib/Jean-Christophe_Plagniol-Villard/qemu_mips/
-you can downland::
+  dd if=/dev/zero bs=1M count=4 | tr '\000' '\377' > pflash.img
+  dd if=${UBOOT_BIN} of=pflash.img conv=notrunc
 
-   #config to build the kernel
-   qemu_mips_defconfig
-   #patch to fix mips interrupt init on 2.6.24.y kernel
-   qemu_mips_kernel.patch
-   initrd.gz
-   vmlinux
-   vmlinux.bin
-   System.map
-
-Generate uImage
-^^^^^^^^^^^^^^^
-
-.. code-block:: bash
-
-   tools/mkimage -A mips -O linux -T kernel -C gzip -a 0x80010000 -e 0x80245650 -n "Linux 2.6.24.y" -d vmlinux.bin.gz uImage
-
-Copy uImage to Flash
-^^^^^^^^^^^^^^^^^^^^
+Start Qemu:
 
 .. code-block:: bash
 
-   dd if=uImage bs=1k conv=notrunc seek=224 of=flash
-
-Generate Ide Disk
-^^^^^^^^^^^^^^^^^
+  mkdir tftproot
+  ${QEMU_BIN} -nographic -cpu ${QEMU_CPU} -m 256 -drive if=pflash,file="$(pwd)/pflash.img",format=raw -netdev user,id=net0,tftp="$(pwd)/tftproot" -device pcnet,netdev=net0
 
 .. code-block:: bash
 
-   dd of=ide bs=1k count=100k if=/dev/zero
+  U-Boot 2021.04-00963-g60279a2b1d (Apr 21 2021 - 19:54:32 +0200)
 
-   # Create partion table
-   sudo sfdisk ide << EOF
-   label: dos
-   label-id: 0x6fe3a999
-   device: image
-   unit: sectors
-   image1 : start=       63, size=    32067, Id=83
-   image2 : start=    32130, size=    32130, Id=83
-   image3 : start=    64260, size=  4128705, Id=83
-   EOF
+  Board: MIPS Malta CoreLV
+  DRAM:  256 MiB
+  Flash: 4 MiB
+  Loading Environment from Flash... *** Warning - bad CRC, using default environment
 
-Copy to ide
-^^^^^^^^^^^
+  In:    serial@3f8
+  Out:   serial@3f8
+  Err:   serial@3f8
+  Net:   pcnet#0
+  IDE:   Bus 0: not available
+  maltael #
 
-.. code-block:: bash
-
-   dd if=uImage bs=512 conv=notrunc seek=63 of=ide
+How to debug U-Boot
+-------------------
 
-Generate ext2 on part 2 on Copy uImage and initrd.gz
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+In order to debug U-Boot you need to start qemu with gdb server support (-s)
+and waiting the connection to start the CPU (-S). Start Qemu in the first console:
 
 .. code-block:: bash
 
-   # Attached as loop device ide offset = 32130 * 512
-   sudo losetup -o 16450560 /dev/loop0 ide
-   # Format as ext2 ( arg2 : nb blocks)
-   sudo mkfs.ext2 /dev/loop0 16065
-   sudo losetup -d /dev/loop0
-   # Mount and copy uImage and initrd.gz to it
-   sudo mount -o loop,offset=16450560 -t ext2 ide /mnt
-   sudo mkdir /mnt/boot
-   cp {initrd.gz,uImage} /mnt/boot/
-   # Umount it
-   sudo umount /mnt
-
-Set Environment
-^^^^^^^^^^^^^^^
-
-.. code-block:: bash
+  mkdir tftproot
+  ${QEMU_BIN} -s -S -nographic -cpu ${QEMU_CPU} -m 256 -drive if=pflash,file="$(pwd)/pflash.img",format=raw -netdev user,id=net0,tftp="$(pwd)/tftproot" -device pcnet,netdev=net0
 
-   setenv rd_start 0x80800000
-   setenv rd_size 2663940
-   setenv kernel BFC38000
-   setenv oad_addr 80500000
-   setenv load_addr2 80F00000
-   setenv kernel_flash BFC38000
-   setenv load_addr_hello 80200000
-   setenv bootargs 'root=/dev/ram0 init=/bin/sh'
-   setenv load_rd_ext2 'ide res; ext2load ide 0:2 ${rd_start} /boot/initrd.gz'
-   setenv load_rd_tftp 'tftp ${rd_start} /initrd.gz'
-   setenv load_kernel_hda 'ide res; diskboot ${load_addr} 0:2'
-   setenv load_kernel_ext2 'ide res; ext2load ide 0:2 ${load_addr} /boot/uImage'
-   setenv load_kernel_tftp 'tftp ${load_addr} /qemu_mips/uImage'
-   setenv boot_ext2_ext2 'run load_rd_ext2; run load_kernel_ext2; run addmisc; bootm ${load_addr}'
-   setenv boot_ext2_flash 'run load_rd_ext2; run addmisc; bootm ${kernel_flash}'
-   setenv boot_ext2_hda 'run load_rd_ext2; run load_kernel_hda; run addmisc; bootm ${load_addr}'
-   setenv boot_ext2_tftp 'run load_rd_ext2; run load_kernel_tftp; run addmisc; bootm ${load_addr}'
-   setenv boot_tftp_hda 'run load_rd_tftp; run load_kernel_hda; run addmisc; bootm ${load_addr}'
-   setenv boot_tftp_ext2 'run load_rd_tftp; run load_kernel_ext2; run addmisc; bootm ${load_addr}'
-   setenv boot_tftp_flash 'run load_rd_tftp; run addmisc; bootm ${kernel_flash}'
-   setenv boot_tftp_tftp 'run load_rd_tftp; run load_kernel_tftp; run addmisc; bootm ${load_addr}'
-   setenv load_hello_tftp 'tftp ${load_addr_hello} /examples/hello_world.bin'
-   setenv go_tftp 'run load_hello_tftp; go ${load_addr_hello}'
-   setenv addmisc 'setenv bootargs ${bootargs} console=ttyS0,${baudrate} rd_start=${rd_start} rd_size=${rd_size} ethaddr=${ethaddr}'
-   setenv bootcmd 'run boot_tftp_flash'
-
-Now you can boot from flash, ide, ide+ext2 and tfp
+In the second console start gdb:
 
 .. code-block:: bash
 
-   qemu-system-mips -M mips -pflash flash -monitor null -nographic -net nic -net user -tftp `pwd` -hda ide
-
-
-How to debug U-Boot
--------------------
-
-In order to debug U-Boot you need to start qemu with gdb server support (-s)
-and waiting the connection to start the CPU (-S)
+  gdb-multiarch --eval-command "target remote :1234" u-boot
 
 .. code-block:: bash
 
-   qemu-system-mips -S -s -M mips -pflash flash -monitor null -nographic -net nic -net user -tftp `pwd` -hda ide
-
-in an other console you start gdb
-
-Debugging of U-Boot Before Relocation
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Before relocation, the addresses in the ELF file can be used without any problems
-by connecting to the gdb server localhost:1234
-
-.. code-block:: none
-
-   $ mipsel-unknown-linux-gnu-gdb u-boot
-   GNU gdb 6.6
-   Copyright (C) 2006 Free Software Foundation, Inc.
-   GDB is free software, covered by the GNU General Public License, and you are
-   welcome to change it and/or distribute copies of it under certain conditions.
-   Type "show copying" to see the conditions.
-   There is absolutely no warranty for GDB.  Type "show warranty" for details.
-   This GDB was configured as "--host=i486-linux-gnu --target=mipsel-unknown-linux-gnu"...
-   (gdb)  target remote localhost:1234
-   Remote debugging using localhost:1234
-   _start () at start.S:64
-   64		RVECENT(reset,0)	/* U-Boot entry point */
-   Current language:  auto; currently asm
-   (gdb)  b board.c:289
-   Breakpoint 1 at 0xbfc00cc8: file board.c, line 289.
-   (gdb) c
-   Continuing.
-
-   Breakpoint 1, board_init_f (bootflag=<value optimized out>) at board.c:290
-   290		relocate_code (addr_sp, id, addr);
-   Current language:  auto; currently c
-   (gdb) p/x addr
-   $1 = 0x87fa0000
-
-Debugging of U-Boot After Relocation
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-For debugging U-Boot after relocation we need to know the address to which
-U-Boot relocates itself to 0x87fa0000 by default.
-And replace the symbol table to this offset.
-
-.. code-block:: none
-
-   (gdb) symbol-file
-   Discard symbol table from `/private/u-boot-arm/u-boot'? (y or n) y
-   Error in re-setting breakpoint 1:
-   No symbol table is loaded.  Use the "file" command.
-   No symbol file now.
-   (gdb) add-symbol-file u-boot 0x87fa0000
-   add symbol table from file "u-boot" at
-   	.text_addr = 0x87fa0000
-   (y or n) y
-   Reading symbols from /private/u-boot-arm/u-boot...done.
-   Breakpoint 1 at 0x87fa0cc8: file board.c, line 289.
-   (gdb) c
-   Continuing.
-
-   Program received signal SIGINT, Interrupt.
-   0xffffffff87fa0de4 in udelay (usec=<value optimized out>) at time.c:78
-   78		while ((tmo - read_c0_count()) < 0x7fffffff)
+  GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2
+  Copyright (C) 2020 Free Software Foundation, Inc.
+  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
+  This is free software: you are free to change and redistribute it.
+  There is NO WARRANTY, to the extent permitted by law.
+  Type "show copying" and "show warranty" for details.
+  This GDB was configured as "x86_64-linux-gnu".
+  Type "show configuration" for configuration details.
+  For bug reporting instructions, please see:
+  <http://www.gnu.org/software/gdb/bugs/>.
+  Find the GDB manual and other documentation resources online at:
+      <http://www.gnu.org/software/gdb/documentation/>.
+
+  For help, type "help".
+  Type "apropos word" to search for commands related to "word"...
+  Reading symbols from u-boot...
+  Remote debugging using :1234
+  0xbfc00000 in ?? ()
+  (gdb) c
+  Continuing.