Re: [PATCH] target/sh4: Remove old README.sh4 file

[Yoshinori Sato]

On Wed, 30 Mar 2022 00:19:55 +0900,
Thomas Huth wrote:
> 
> This file didn't have any non-trivial update since it was initially
> added in 2006, and looking at the content, it seems incredibly outdated,
> saying e.g. "The sh4 target is not ready at all yet for integration in
> qemu" or "A sh4 user-mode has also somewhat started but will be worked
> on afterwards"... Sounds like nobody is interested in this README file
> anymore, so let's simply remove it now.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  target/sh4/README.sh4 | 150 ------------------------------------------
>  1 file changed, 150 deletions(-)
>  delete mode 100644 target/sh4/README.sh4
> 
> diff --git a/target/sh4/README.sh4 b/target/sh4/README.sh4
> deleted file mode 100644
> index a192ca7540..0000000000
> --- a/target/sh4/README.sh4
> +++ /dev/null
> @@ -1,150 +0,0 @@
> -qemu target:   sh4
> -author:        Samuel Tardieu <sam@rfc1149.net>
> -last modified: Tue Dec  6 07:22:44 CET 2005
> -
> -The sh4 target is not ready at all yet for integration in qemu. This
> -file describes the current state of implementation.
> -
> -Most places requiring attention and/or modification can be detected by
> -looking for "XXXXX" or "abort()".
> -
> -The sh4 core is located in target/sh4/*, while the 7750 peripheral
> -features (IO ports for example) are located in hw/sh7750.[ch]. The
> -main board description is in hw/shix.c, and the NAND flash in
> -hw/tc58128.[ch].
> -
> -All the shortcomings indicated here will eventually be resolved. This
> -is a work in progress. Features are added in a semi-random order: if a
> -point is blocking to progress on booting the Linux kernel for the shix
> -board, it is addressed first; if feedback is necessary and no progress
> -can be made on blocking points until it is received, a random feature
> -is worked on.
> -
> -Goals
> ------
> -
> -The primary model being worked on is the soft MMU target to be able to
> -emulate the Shix 2.0 board by Alexis Polti, described at
> -https://web.archive.org/web/20070917001736/http://perso.enst.fr/~polti/realisations/shix20/
> -
> -Ultimately, qemu will be coupled with a system C or a verilog
> -simulator to simulate the whole board functionalities.
> -
> -A sh4 user-mode has also somewhat started but will be worked on
> -afterwards. The goal is to automate tests for GNAT (GNU Ada) compiler
> -that I ported recently to the sh4-linux target.
> -
> -Registers
> ----------
> -
> -16 general purpose registers are available at any time. The first 8
> -registers are banked and the non-directly visible ones can be accessed
> -by privileged instructions. In qemu, we define 24 general purpose
> -registers and the code generation use either [0-7]+[8-15] or
> -[16-23]+[8-15] depending on the MD and RB flags in the sr
> -configuration register.
> -
> -Instructions
> -------------
> -
> -Most sh4 instructions have been implemented. The missing ones at this
> -time are:
> -  - FPU related instructions
> -  - LDTLB to load a new MMU entry
> -  - SLEEP to put the processor in sleep mode
> -
> -Most instructions could be optimized a lot. This will be worked on
> -after the current model is fully functional unless debugging
> -convenience requires that it is done early.
> -
> -Many instructions did not have a chance to be tested yet. The plan is
> -to implement unit and regression testing of those in the future.
> -
> -MMU
> ----
> -
> -The MMU is implemented in the sh4 core. MMU management has not been
> -tested at all yet. In the sh7750, it can be manipulated through memory
> -mapped registers and this part has not yet been implemented.
> -
> -Exceptions
> -----------
> -
> -Exceptions are implemented as described in the sh4 reference manual
> -but have not been tested yet. They do not use qemu EXCP_ features
> -yet.
> -
> -IRQ
> ----
> -
> -IRQ are not implemented yet.
> -
> -Peripheral features
> --------------------
> -
> -  + Serial ports
> -
> -Configuration and use of the first serial port (SCI) without
> -interrupts is supported. Input has not yet been tested.
> -
> -Configuration of the second serial port (SCIF) is supported. FIFO
> -handling infrastructure has been started but is not completed yet.
> -
> -  + GPIO ports
> -
> -GPIO ports have been implemented. A registration function allows
> -external modules to register interest in some port changes (see
> -hw/tc58128.[ch] for an example) and will be called back. Interrupt
> -generation is not yet supported but some infrastructure is in place
> -for this purpose. Note that in the current model a peripheral module
> -cannot directly simulate a H->L->H input port transition and have an
> -interrupt generated on the low level.
> -
> -  + TC58128 NAND flash
> -
> -TC58128 NAND flash is partially implemented through GPIO ports. It
> -supports reading from flash.
> -
> -GDB
> ----
> -
> -GDB remote target support has been implemented and lightly tested.
> -
> -Files
> ------
> -
> -File names are hardcoded at this time. The bootloader must be stored in
> -shix_bios.bin in the current directory. The initial Linux image must
> -be stored in shix_linux_nand.bin in the current directory in NAND
> -format. Test files can be obtained from
> -http://perso.enst.fr/~polti/robot/ as well as the various datasheets I
> -use.
> -
> -qemu disk parameter on the command line is unused. You can supply any
> -existing image and it will be ignored. As the goal is to simulate an
> -embedded target, it is not clear how this parameter will be handled in
> -the future.
> -
> -To build an ELF kernel image from the NAND image, 16 bytes have to be
> -stripped off the end of every 528 bytes, keeping only 512 of them. The
> -following Python code snippet does it:
> -
> -#! /usr/bin/python
> -
> -def denand (infd, outfd):
> -    while True:
> -        d = infd.read (528)
> -        if not d: return
> -        outfd.write (d[:512])
> -
> -if __name__ == '__main__':
> -    import sys
> -    denand (open (sys.argv[1], 'rb'),
> -            open (sys.argv[2], 'wb'))
> -
> -Style isssues
> --------------
> -
> -There is currently a mix between my style (space before opening
> -parenthesis) and qemu style. This will be resolved before final
> -integration is proposed.
> -- 
> 2.27.0
> 

Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp>

-- 
Yosinori Sato