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Date:   Tue, 1 Feb 2022 08:44:57 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Guo Ren <guoren@kernel.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Anup Patel <anup@brainfault.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        liush <liush@allwinnertech.com>, Wei Fu <wefu@redhat.com>,
        Drew Fustini <drew@beagleboard.org>,
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        Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH V4 16/17] riscv: compat: Add COMPAT Kbuild skeletal
 support
Message-ID: <20220201074457.GC29119@lst.de>
References: <20220129121728.1079364-1-guoren@kernel.org> <20220129121728.1079364-17-guoren@kernel.org> <YffVZZg9GNcjgVdm@infradead.org> <CAJF2gTRXDotO1L1FMojQs6msrqvCzA782Pux8rg3AfZgA=y0ew@mail.gmail.com>
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On Mon, Jan 31, 2022 at 09:50:58PM +0800, Guo Ren wrote:
> On Mon, Jan 31, 2022 at 8:26 PM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > Given that most rv64 implementations can't run in rv32 mode, what is the
> > failure mode if someone tries it with the compat mode enabled?
> A static linked simple hello_world could still run on a non-compat
> support hardware. But most rv32 apps would meet different userspace
> segment faults.
> 
> Current code would let the machine try the rv32 apps without detecting
> whether hw support or not.

Hmm, we probably want some kind of check for not even offer running
rv32 binaries.  I guess trying to write UXL some time during early
boot and catching the resulting exception would be the way to go?

> 
> 
> -- 
> Best Regards
>  Guo Ren
> 
> ML: https://lore.kernel.org/linux-csky/
---end quoted text---