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[222.155.6.212]) by smtp.gmail.com with ESMTPSA id a25sm1681355pfo.200.2021.08.24.01.45.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Aug 2021 01:45:15 -0700 (PDT) Subject: Re: RFC: remove set_fs for m68k To: Linus Torvalds References: <65a95ae0-4734-68ce-ef71-7491b5534718@gmail.com> <8f470389-fe8a-90b0-19a5-68f85526b30e@gmail.com> <20210721170529.GA14550@lst.de> <20210723051126.GA31274@lst.de> <8884e940-22e8-72a5-e9ec-f9b2628b6ef4@gmail.com> <251aa093-047a-b37c-4e88-d543c6fa8bc6@gmail.com> <20210815074236.GA23777@lst.de> <63c35a20-3eec-1825-fa18-5df28f5b6eaa@gmail.com> <20210816065851.GA26665@lst.de> <7517d306-21ad-daa1-a2fb-b273211cb588@gmail.com> Cc: Christoph Hellwig , Andreas Schwab , Geert Uytterhoeven , Greg Ungerer , linux-m68k From: Michael Schmitz Message-ID: <57501cee-de70-99e5-3a92-e5d2a515bb51@gmail.com> Date: Tue, 24 Aug 2021 20:44:31 +1200 User-Agent: Mozilla/5.0 (X11; Linux ppc64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Thanks Linus (and Andreas), On 24/08/21 09:49, Linus Torvalds wrote: > On Mon, Aug 23, 2021 at 2:31 PM Michael Schmitz wrote: >> Hi Linus, >> >> >> On 24/08/21 05:59, Linus Torvalds wrote: >>> On Sun, Aug 22, 2021 at 12:34 PM Michael Schmitz wrote: >>>> Got this overnight: >>>> >>>>> [536154.200000] *** FORMAT ERROR *** FORMAT=0 >>>>> [536154.210000] Current process id is 4656 >>>>> [536154.230000] BAD KERNEL TRAP: 00000000 >>>>> [536154.240000] Modules linked in: atari_scsi ne 8390p [last unloaded: atari_scsi] >>>>> [536154.260000] PC: [<00002a8c>] resume_userspace+0x14/0x16 >>>>> [536154.270000] SR: 2208 SP: 977bd1be a2: 8009b5e8 >>>>> [536154.290000] d0: 8009b5e8 d1: cfcfcfcf d2: 00000000 d3: ffffffff >>>>> [536154.300000] d4: 00000000 d5: 00000000 a0: 8008a108 a1: 8009b7df >>>>> [536154.320000] Process savelog (pid: 4656, task=e49aa246) >>>>> [536154.330000] Frame format=0 >>>>> [536154.340000] Stack from 00cc5fa4: >>>>> [536154.340000] 02088004 3666b008 1c0eb209 007eb5e8 8006a2d0 efaec378 8004366c 61ff61ff >>>>> [536154.340000] 8006a2d4 8006a2d2 00000000 030dfffb 0044fffa 0e000000 fffa1a00 fffa1c00 >>>>> [536154.340000] fffa1e00 fffb0e40 fffb0e80 00049b66 00000040 005f5800 00000001 >>> Strange. If I read that stack frame correctly, that seems to be an >>> exception frame of type 0xb ("Long Bus Cycle"). >> Not sure where you get the 0xb from - the frame format I see is 0. > The "Frame format=0" is, afaik, the format of when the error happens. > > But I'm looking at what the stack contents are at the time of the > exception, to see what actually *triggered* the error. > > And if I read it right, the RTE that took the format error fault had this stack: > > 02088004 3666b008 1c0eb209 .. > > and that means that it tried to return with status register 0208 > (which looks correct: supervisor bit clear), to PC 80043666 (which > might be right - it's a similar address to the ones in A0/A1). I see - found some information on the 030 exception stack frame format online now. > > And then the format/vector value is b008. > > That is, if I read it right, format 0xb, which is that "Long Bus Cycle" thing. > > NOTE! I may be misreading this entirely. My m68k knowledge is so > out-of-date that it's not even funny, and it actually predates all > this fancy format stuff. So I'm just pattern-matching with the manuals > I found online. I'll take your word for it (especially after Andreas confirmed it :-). The information in our show_registers ought to be enough for me to decode the various faults of this type I've seen, and spot any patterns. Cheers, Michael