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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=4tLhNFY5eM/BdsleL4+JFzAGJ97N80D9JBWUDFZUx1k=; b=Ryw1LSHysutICx+3z1sw59BVJLpn1x4WAuX4RnJ8iSs1dRDHyEP/fXbP/G5LfydHrP 2ChraZvXP7o0hBvtpW2NQrDh+6lfUzUf0Q9tssHeR85ftt+vJGUP9UI2Ti6AlsCZP/IX W10ZeE/Mp/yjSHbxuD1cJDAZ6v0rmkBlP9PnBUjSqBhHNVwky7mmA1Slc4jtJTpr+1U/ CozdBkFKSh5i2279AKh+Q5miVPH02y7y+uLlXBwvdbxDFxFiBfheH+DlclrP35r70bdv rvOal/78xKLKkr4z4dUaWbrSntYP0IzcEMA3Kw45cOoMNbiFe3BDFddUUar7nztJLhT1 AHng== X-Gm-Message-State: AOAM531AD8qdxSHOEkXRqHoSuIGTNxvalrJeUrLwq9M+vPTEO6k72R7D 6vyoKHphPNS2X3JUu/JbdIxhVJU2SFB27w== X-Google-Smtp-Source: ABdhPJzTC6/gfblUOTbiqvijeafYrWS4uD9j91I5Xm/KC+hqKqRtz8CI6dSFUPz6Jo4J+xz6LXKYMw== X-Received: by 2002:a1c:4489:: with SMTP id r131mr1282834wma.24.1610490207146; Tue, 12 Jan 2021 14:23:27 -0800 (PST) Subject: Re: [PATCH V3 09/23] xen/dm: Make x86's DM feature common From: Oleksandr To: Jan Beulich Cc: Julien Grall , Paul Durrant , Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Daniel De Graaf , Oleksandr Tyshchenko , xen-devel@lists.xenproject.org References: <1606732298-22107-1-git-send-email-olekstysh@gmail.com> <1606732298-22107-10-git-send-email-olekstysh@gmail.com> <00c3df9f-760d-bb3d-d1d6-7c7df7f0c17c@suse.com> <24191fca-78e7-3e6b-ff02-c06e8ae79f56@gmail.com> <7c985117-2bb4-dd5b-53cf-e217e25b2e8e@suse.com> <94c20a50-9363-c8d1-11aa-7a35f97a03a6@gmail.com> <318580a5-d02f-9663-cc58-dfad8a4f7836@suse.com> <7ca63ab6-85c8-2b5a-2be9-dcb4aaed7ac3@gmail.com> Message-ID: <87036ec1-0bb4-43a4-60c1-25ced6ac0a97@gmail.com> Date: Wed, 13 Jan 2021 00:23:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <7ca63ab6-85c8-2b5a-2be9-dcb4aaed7ac3@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Hi Jan. On 07.01.21 18:49, Oleksandr wrote: > > On 07.01.21 17:01, Jan Beulich wrote: > > Hi Jan, all > >> On 07.01.2021 15:38, Oleksandr wrote: >>>>> Well, on v2 you replied you didn't consider the alternative. I would >>>>> have expected that you would at least go through this consideration >>>>> process, and see whether there are better reasons to stick with the >>>>> apparently backwards arrangement than to change to the more >>>>> conventional one. If there are such reasons, I would expect them to >>>>> be called out in reply and perhaps also in the commit message; the >>>>> latter because down the road more people may wonder why the more >>>>> narrow / special set of cases gets handled at a higher layer than >>>>> the wider set of remaining ones, and they would then be able to find >>>>> an explanation without having to resort to searching through list >>>>> archives. >>>> Ah, will investigate. Sorry for not paying enough attention to it. >>>> Yes, IOREQ (I mean "common") ops are 7 out of 18 right now. The >>>> subsequent patch is adding one more DM op - XEN_DMOP_set_irq_level. >>>> There are several PCI related ops which might want to be common in the >>>> future (but I am not sure). >>> I think, I can say that I have considered the alternative (doing it the >>> other way around), of course if I got your suggestion for V2 correctly. >>> Agree, the alternative is more natural, also compat_dm_op() was left in >>> x86 code. For me the downside is in code duplication. With the >>> alternative both arches have to duplicate do_dm_op() and "common" part >>> of dm_op() >>> (only "switch ( op.op )" is unique). >> Yes, this duplication is the main downside. >> >>> Now the question is which approach to take ("current" or "alternative") >>> for me to prepare for V4. Personally, I would be OK with the both (with >>> a little preference for "alternative"). >> Same here. I don't think I've seen anyone else voice an opinion. > > Well, let's wait a bit for other opinions... @Julien, @Paul what do > you think on that? > > >> >>> Also, If we decide to go with the alternative, should the common files >>> still be named dm.*? >> I think this should live in ioreq.c, just like e.g. >> iommu_do_pci_domctl() lives in passthrough/pci.c. This would then >> allow quite a few things to become static in that file, I believe. > > I got it. It seems yes, at least the following could became static: > > ioreq_server_create > ioreq_server_get_info > ioreq_server_map_io_range > ioreq_server_unmap_io_range > ioreq_server_set_state > ioreq_server_destroy Well, I have already pushed V4 with this "alternative" approach, let's discuss there [1]. [1] https://lore.kernel.org/xen-devel/1610488352-18494-10-git-send-email-olekstysh@gmail.com/T/#mb08f75657f43df869596c5c9c30e2395a9e35c7a -- Regards, Oleksandr Tyshchenko