From: Greg Ungerer <gerg@linux-m68k.org>
To: Rob Landley <rob@landley.net>, Finn Thain <fthain@linux-m68k.org>
Cc: Daniel Palmer <daniel@0x0f.com>, Arnd Bergmann <arnd@arndb.de>,
Christoph Hellwig <hch@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
"moderated list:H8/300 ARCHITECTURE"
<uclinux-h8-devel@lists.sourceforge.jp>,
"open list:TENSILICA XTENSA PORT (xtensa)"
<linux-xtensa@linux-xtensa.org>,
Max Filippov <jcmvbkbc@gmail.com>,
Linux-sh list <linux-sh@vger.kernel.org>,
linux-m68k <linux-m68k@lists.linux-m68k.org>,
Damien Le Moal <damien.lemoal@wdc.com>,
linux-riscv <linux-riscv@lists.infradead.org>
Subject: Re: [RFC PULL] remove arch/h8300
Date: Thu, 14 Apr 2022 10:49:40 +1000 [thread overview]
Message-ID: <7a26156e-1f06-b0b1-2859-432a75e9e0d4@linux-m68k.org> (raw)
In-Reply-To: <ae4125f5-e725-43ed-d05b-b1f88c0cd50c@landley.net>
On 10/4/22 17:26, Rob Landley wrote:
>
>
> On 4/8/22 23:18, Greg Ungerer wrote:
>>
>> On 9/4/22 11:59, Finn Thain wrote:
>>> On Fri, 8 Apr 2022, Rob Landley wrote:
>>>
>>>> On 4/5/22 08:07, Greg Ungerer wrote:
>>>>> On 5/4/22 13:23, Daniel Palmer wrote:
>>>>>> On Mon, 4 Apr 2022 at 22:42, Greg Ungerer <gerg@linux-m68k.org> wrote:
>>>>>>> But we could consider the Dragonball support for removal. I keep it
>>>>>>> compiling, but I don't use it and can't test that it actually works.
>>>>>>> Not sure that it has been used for a very long time now. And I
>>>>>>> didn't even realize but its serial driver (68328serial.c) was
>>>>>>> removed in 2015. No one seems too have noticed and complained.
>>>>>>
>>>>>> I noticed this and I am working on fixing it up for a new Dragonball
>>>>>> homebrew machine. I'm trying to add a 68000 machine to QEMU to make
>>>>>> the development easier because I'm currently waiting an hour or more
>>>>>> for a kernel to load over serial. It might be a few months.
>>>>
>>>> I've been booting Linux on qemu-system-m68k -M q800 for a couple years
>>>> now? (The CROSS=m68k target of mkroot in toybox?)
>>>>
>>>> # cat /proc/cpuinfo
>>>> CPU: 68040
>>>> MMU: 68040
>>>> FPU: 68040
>>>> Clocking: 1261.9MHz
>>>> BogoMips: 841.31
>>>> Calibration: 4206592 loops
>>>>
>>>> It certainly THINKS it's got m68000...
>>>>
>>>
>>> Most 68040 processor variants have a built-in MMU and the m68k "nommu"
>>> Linux port doesn't support them. The nommu port covers processors like
>>> 68000, Dragonball etc. whereas the m68k "mmu" port covers 680x0 where x is
>>> one of 2,3,4,6 with MMU.
>
> In theory you can switch the MMU off. (Or at least give it a NOP page table that
> maps all the physical memory into one big contiguous block 1:1 with the physical
> address and leave it there.)
>
> Doesn't mean anybody's bothered to implement and add a config option to stub
> that out in the kernel yet. But presumably you could have a bootloader shim do it...
>
>>>> (I'd love to get an m68k nommu system working but never sat down and
>>>> worked out a kernel .config qemu agreed to run, plus compiler and libc.
>>>> Musl added m68k support but I dunno if that includes coldfire?)
>>>>
>>>
>>> I could never figure out how to boot a coldfire machine in qemu either.
>>> There was no documentation about that back when I attempted it but maybe
>>> things have improved since.
>>
>> FWIW this will do it:
>>
>> qemu-system-m68k -nographic -machine mcf5208evb -kernel vmlinux
>>
>> That will boot an m5208evb_defconfig generated vmlinux.
>> But you will need a user space to get a full boot to login/shell.
>
> No FDPIC support. :(
>
> I had a binflt toolchain working with uClibc in 2015 or so, but I end of lifed
> https://landley.net/aboriginal in 2017 (five years ago now). Multiple reasons,
> but one was the old "last GPLv2 release" toolchain was getting painful to force
> the kernel to build with.
>
> These days there's articles on lwn.net about yanking a.out support, which fdpic
> is a buggy variant of that didn't actually have a maintained elf2flt repository
> when I was assembling my toolchain. (I vaguely recall I poked enough people that
> somebody picked it up and stuck a repository on github, but Jeff Dionne
> explained some fundamental design flaw that had been introduced having to do
> with register offsets being calculated in the wrong framework or something?
>
> I don't remember, I lost interest because it's _conceptually_ obsolete. FDPIC is
> ELF with a little extra header info, it's clean and potentially even useful on
> with-MMU systems as extra ASLR. BINFLT is a.out run through a postprocessing
> tool that nominally converts ELF files into the new format but actually needs .o
> files from earlier in the process and is kind of an alternate linker except it
> doesn't replace the linker... It's layers of ugly.
FLAT format has nothing to do with a.out.
Removing a.out support from the kernel will have no impact on binfmt_flat.
Regards
Greg
next prev parent reply other threads:[~2022-04-14 0:49 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-08 6:52 [RFC PULL] remove arch/h8300 Christoph Hellwig
2022-03-08 8:19 ` Arnd Bergmann
2022-04-03 12:43 ` Christoph Hellwig
2022-04-04 13:07 ` Arnd Bergmann
2022-04-04 13:09 ` John Paul Adrian Glaubitz
2022-04-04 13:22 ` Geert Uytterhoeven
2022-04-04 23:34 ` Damien Le Moal
2022-04-06 21:25 ` Rob Landley
2022-04-07 7:17 ` Arnd Bergmann
2022-04-07 7:47 ` John Paul Adrian Glaubitz
2022-04-07 7:52 ` Christoph Hellwig
2022-04-07 8:34 ` Finn Thain
2022-04-04 13:41 ` Greg Ungerer
2022-04-05 3:23 ` Daniel Palmer
2022-04-05 13:07 ` Greg Ungerer
2022-04-09 0:24 ` Rob Landley
2022-04-09 1:59 ` Finn Thain
2022-04-09 4:18 ` Greg Ungerer
2022-04-10 7:26 ` Rob Landley
2022-04-10 8:08 ` Rob Landley
2022-04-14 0:49 ` Greg Ungerer [this message]
2022-04-09 3:37 ` Daniel Palmer
2022-04-10 7:13 ` Rob Landley
2022-04-09 4:14 ` Greg Ungerer
2022-04-04 17:57 ` Max Filippov
2022-04-04 19:01 ` Arnd Bergmann
2022-04-04 19:14 ` Max Filippov
2022-04-04 19:35 ` Arnd Bergmann
2022-04-04 19:44 ` Arnd Bergmann
2022-04-04 20:56 ` Max Filippov
2022-04-04 20:48 ` Max Filippov
2022-04-04 23:32 ` Damien Le Moal
2022-04-05 21:26 ` Guenter Roeck
2022-04-05 22:01 ` Arnd Bergmann
2022-04-06 0:12 ` Guenter Roeck
2022-05-06 14:07 ` Geert Uytterhoeven
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