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Subject: Re: [PATCH] m68k: mm: Remove check for VM_IO to fix deferred I/O
To:     Finn Thain <fthain@linux-m68k.org>
References: <20220128173006.1713210-1-geert@linux-m68k.org>
 <b1cd50eb-e476-b4bd-0b2f-b4a8699660f6@gmail.com>
 <4d65d2e1-5fb3-456-3cc5-fbd3167d06c@linux-m68k.org>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-m68k@lists.linux-m68k.org,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org
From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <2ff869af-87a5-898c-b863-18e48527464b@gmail.com>
Date:   Sat, 29 Jan 2022 15:08:46 +1300
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Hi Finn,

Am 29.01.2022 um 12:55 schrieb Finn Thain:
> On Sat, 29 Jan 2022, Michael Schmitz wrote:
>
>> Hi Geert,
>>
>> for hwregs_present(), the exception fixup will handle any access error
>> (through send_fault_sig()), so this should continue to work.
>>
>> Why the special handling of VM_IO pages? Maybe hp300 had marked all IO
>> register pages VM_IO to distinguish IO faults from VM faults...
>>
>> The only other area I can imagine this might have an impact is the Mac's
>> pseudo-DMA - FInn might want to give this some testing.
>>
>
> mac_scsi.c and mac_esp.c don't use ioremap(). They rely on head.S:
>
>         mmu_map_eq      #0x50000000,#0x03000000,%d3
>
> Having said that, I will run some tests if you still think it necessary.

No need for test then, thanks!

Cheers,

	Michael