Date: Thu, 25 May 2023 21:40:04 +0300 From: Vitaliy Gusev <gusev.vitaliy@gmail.com> To: Mario Marietto <marietto2008@gmail.com> Cc: Tomek CEDRO <tomek@cedro.info>, virtualization@freebsd.org, freebsd-hackers@freebsd.org Subject: Re: BHYVE SNAPSHOT image format proposal Message-ID: <D243949C-4C2E-4C6E-8961-7534DD2CCD00@gmail.com> In-Reply-To: <CA%2B1FSijKkCnR5j1N9BN0CbqzzitibK7r9OA84jc2eZ=uJaMW-g@mail.gmail.com> References: <67FDC8A8-86A6-4AE4-85F0-FF7BEF9F2F06@gmail.com> <CAFYkXjng1LWy5wVyTnSo0xrEWOy%2BOx9ZjLcmFqQs5EVpT8J_uA@mail.gmail.com> <AF34E648-2D8A-46C7-82A5-B88006BBB8F6@gmail.com> <CAFYkXjkUjh8gEMv4XZgb2QQW=qM1fhxMoMxRYuc4p6HbBXsDCw@mail.gmail.com> <8FE14143-1AA9-418E-A497-FEFB99BF6B9F@gmail.com> <CA%2B1FSijKkCnR5j1N9BN0CbqzzitibK7r9OA84jc2eZ=uJaMW-g@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
--Apple-Mail=_9EC57A81-2637-440C-A2F4-5E1697C8811A Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On 25 May 2023, at 19:22, Mario Marietto <marietto2008@gmail.com> = wrote: >=20 > Vitaliy, >=20 > what happens if I clone your repo as source code on my FreeBSD system. = Can I test your code directly or not ? Anyway,I think that,before doing = this,I need to follow some kind of tutorial,to understand how the = workflow is. Otherwise I will be not able to test and stress it.=20 You should build kernel and tools, install it. Then you can run bhyve, = bhyvectl to deal with suspend/resume. Please follow=20 9.5. Building and Installing a Custom Kernel https://docs.freebsd.org/en/books/handbook/book/#kernelconfig-building Make sure that BHYVE_SNAPSHOT is enabled. Also look at build(7): https://man.freebsd.org/cgi/man.cgi?build(7) >=20 > On Thu, May 25, 2023 at 3:40=E2=80=AFPM Vitaliy Gusev = <gusev.vitaliy@gmail.com <mailto:gusev.vitaliy@gmail.com>> wrote: >>=20 >>=20 >>> On 25 May 2023, at 04:30, Tomek CEDRO <tomek@cedro.info = <mailto:tomek@cedro.info>> wrote: >>>=20 >>> On Wed, May 24, 2023 at 5:11=E2=80=AFPM Vitaliy Gusev wrote: >>>> Protecting requires more efforts and it should be clearly defined: = what is purpose. If >>>> purpose is having checksum with 99.9% reliability, NVLIST HEADER = can be widen >>>> to have =E2=80=9Cchecksum=E2=80=9D key/value for a Section. >>>=20 >>> Well, this could be optional but useful to make sure snapshot did = not >>> break somehow for instance backup medium error or something like >>> that.. even more maybe a way to fix it.. just a design stage idea :- >>=20 >> Yes, new format can have checksum of a Section data if implemented. >>=20 >>>=20 >>>=20 >>>> If purpose is having crypto verification - I believe sha256 program = should be your choice. >>>=20 >>> My question was more specific to availability of that feature >>> (integrity + repair) rather than specific format :-) >>>=20 >>> The use case here is having a virtual machine (it was VirtualBox) = with >>> a bare os installed, plus some common applications, that is = snapshoted >>> at some point in time, then experimented a lot, restored from >>> snapshot, etc. I had a backup of such vm + snapshot backed up that = got >>> broken somehow. It would be nice to know that something is broken, >>> what is broken, maybe a way to fix :-) >>=20 >>=20 >> =E2=80=9CIntegrity" is a very broad term. What checksum algorithm is = fine enough? >> =20 >> For the instance, ZFS has several options for checksum: >>=20 >> = checksum=3Don|off|fletcher2|fletcher4|sha256|noparity|sha512|skein|edonr >> =20 >>=20 >> Having checksum for a filesystem is strongly recommended. However, If = consider image format, >> it doesn=E2=80=99t need to care about consistency in a file itself. = As example (!) - binary files in a system. >> They don=E2=80=99t have checksum integrated, validation is done by = another program - pkg or another. >>=20 >>=20 >>>=20 >>>=20 >>>> Why do you need modify snapshot image ? Could you describe more? Do = you >>>> modify current 3 snapshot files? >>>=20 >>> Analysis that require ram / nvram modification? Not sure if this is >>> already possible, but may come handy for experimenting with uefi and >>> maybe some OS (features) that will not run with unmodified nvram :-P >>=20 >>=20 >> Sorry I don=E2=80=99t get, why do you need to modify snapshot image, = but not directly vmem on the running >> VM? >>=20 >> Another question, checksum and modifying image - two mutual exclusive = things.=20 >>=20 >>>=20 >>>=20 >>>> If you are talking about compatibility of a Image format - it = should be compatible in >>>> both directions, at least for not so big format changes. >>>>=20 >>>> If consider overall snapshot/resume compatibility - I believe = forward compatibility >>>> is not case and target. Indeed, why do you need to resume an image = created by >>>> a higher version of a program? >>>=20 >>> This happens quite often. For instance there is a bug in application >>> and I need to revert to (at least) one step older version. Then I am >>> unable to work on a file that I just saved (or was autosaved for = me). >>> Firefox profile settings let be the first example. KiCAD file format >>> is another example (sometimes I need to switch to a devel build to >>> evade a nasty blocker bug then anyone else that uses a release is >>> blocked for some months including me myself). >>=20 >> Any additional thing has a cost of development, testing and support. = Current >> Implementation doesn=E2=80=99t support compatibility at all. Having = compatibility in both >> directions can be hard. >>=20 >> For example, if some variable is removed in bhyve, backward = compatibility is fine, >> but forward compatibly is not possible unless that removed variable = is being saved >> into a snapshot image just for forward compatibility. And of course, = it should be tested >> and verified as worked. >>=20 >> Do you like that approach? I don=E2=80=99t think so. So I guess only = backward compatibility >> should be supported to make the snapshot code simple and robust. >>=20 >> Thanks, >> Vitaliy Gusev >>=20 >>=20 >=20 >=20 > --=20 > Mario. --Apple-Mail=_9EC57A81-2637-440C-A2F4-5E1697C8811A Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 <html><head><meta http-equiv=3D"content-type" content=3D"text/html; = charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; = -webkit-nbsp-mode: space; line-break: = after-white-space;"><br><div><br><blockquote type=3D"cite"><div>On 25 = May 2023, at 19:22, Mario Marietto <marietto2008@gmail.com> = wrote:</div><br class=3D"Apple-interchange-newline"><div><div = dir=3D"ltr"><div>Vitaliy,</div><div><br></div><div>what happens if I = clone your repo as source code on my FreeBSD system. Can I test your = code directly or not ? Anyway,I think that,before doing this,I need to = follow some kind of tutorial,to understand how the workflow is. = Otherwise I will be not able to test and stress it. = <br></div></div></div></blockquote><div><br></div><div><br></div>You = should build kernel and tools, install it. Then you can run bhyve, = bhyvectl to deal with suspend/resume.</div><div><br></div><div>Please = follow </div><div><br></div><div> <span style=3D"caret-color: = rgb(68, 68, 68); color: rgb(68, 68, 68); font-family: "inter = var", -apple-system, BlinkMacSystemFont, "avenir next", = avenir, "segoe ui", "helvetica neue", helvetica, = Cantarell, Ubuntu, roboto, noto, arial, sans-serif; font-size: = var(--size-550);"><b>9.5. Building and Installing a Custom = Kernel</b></span></div><div><br></div><div><a = href=3D"https://docs.freebsd.org/en/books/handbook/book/#kernelconfig-buil= ding">https://docs.freebsd.org/en/books/handbook/book/#kernelconfig-buildi= ng</a><br></div><div><br></div><div><br></div><div>Make sure that = BHYVE_SNAPSHOT is enabled.</div><div><br></div><div>Also look at = build(7):</div><div><br></div><div><a = href=3D"https://man.freebsd.org/cgi/man.cgi?build(7)">https://man.freebsd.= org/cgi/man.cgi?build(7)</a></div><div><br></div><div><br><blockquote = type=3D"cite"><div><br><div class=3D"gmail_quote"><div dir=3D"ltr" = class=3D"gmail_attr">On Thu, May 25, 2023 at 3:40=E2=80=AFPM Vitaliy = Gusev <<a = href=3D"mailto:gusev.vitaliy@gmail.com">gusev.vitaliy@gmail.com</a>> = wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px = 0px 0px 0.8ex;border-left:1px solid = rgb(204,204,204);padding-left:1ex"><div><br><div><br><blockquote = type=3D"cite"><div>On 25 May 2023, at 04:30, Tomek CEDRO <<a = href=3D"mailto:tomek@cedro.info" = target=3D"_blank">tomek@cedro.info</a>> wrote:</div><br><div><div>On = Wed, May 24, 2023 at 5:11=E2=80=AFPM Vitaliy Gusev wrote:<br><blockquote = type=3D"cite">Protecting requires more efforts and it should be clearly = defined: what is purpose. If<br>purpose is having checksum with 99.9% = reliability, NVLIST HEADER can be widen<br>to have =E2=80=9Cchecksum=E2=80= =9D key/value for a Section.<br></blockquote><br>Well, this could be = optional but useful to make sure snapshot did not<br>break somehow for = instance backup medium error or something like<br>that.. even more maybe = a way to fix it.. just a design stage idea = :-</div></div></blockquote><br>Yes, new format can have checksum of a = Section data if implemented.</div><div><br><blockquote = type=3D"cite"><div><div><br><br><blockquote type=3D"cite">If purpose is = having crypto verification - I believe sha256 program should be your = choice.<br></blockquote><br>My question was more specific to = availability of that feature<br>(integrity + repair) rather than = specific format :-)<br><br>The use case here is having a virtual machine = (it was VirtualBox) with<br>a bare os installed, plus some common = applications, that is snapshoted<br>at some point in time, then = experimented a lot, restored from<br>snapshot, etc. I had a backup of = such vm + snapshot backed up that got<br>broken somehow. It would be = nice to know that something is broken,<br>what is broken, maybe a way to = fix = :-)<br></div></div></blockquote><div><br></div><div><br></div><div> =E2= =80=9CIntegrity" is a very broad term. What checksum algorithm is fine = enough?</div><div> </div><div>For the instance, ZFS has = several options for checksum:</div><div><br></div></div><blockquote = style=3D"margin:0px 0px 0px 40px;border:medium = none;padding:0px"><div><div><div style=3D"margin: 0px; font-style: = normal; font-variant-caps: normal; font-stretch: normal; font-size: = 12px; line-height: normal; font-family: Menlo; font-size-adjust: none; = font-kerning: auto; font-variant-alternates: normal; = font-variant-ligatures: normal; font-variant-numeric: normal; = font-variant-east-asian: normal; font-feature-settings: normal; = background-color: rgb(231, 238, 238);"><span = style=3D"font-variant-ligatures:no-common-ligatures;color:rgb(231,238,238)= ;background-color:rgb(0,0,0)"><b>checksum</b></span><span = style=3D"font-variant-ligatures:no-common-ligatures">=3D<b>on</b>|<b>off</= b>|<b>fletcher2</b>|<b>fletcher4</b>|<b>sha256</b>|<b>noparity</b>|<b>sha5= 12</b>|<b>skein</b>|<b>edonr</b></span></div></div></div><div><div><p = style=3D"margin:0px;font-style:normal;font-variant-caps:normal;font-stretc= h:normal;font-size:12px;line-height:normal;font-family:Menlo;font-size-adj= ust:none;font-kerning:auto;font-variant-alternates:normal;font-variant-lig= atures:normal;font-variant-numeric:normal;font-variant-east-asian:normal;f= ont-feature-settings:normal;background-color:rgb(231,238,238)"><span = style=3D"font-variant-ligatures:no-common-ligatures"> = = </span></p></div></div></blockquote><div><br></div><div>Having = checksum for a filesystem is strongly recommended. However, If consider = image format,</div><div>it doesn=E2=80=99t need to care about = consistency in a file itself. As example (!) - binary files in a = system.</div><div>They don=E2=80=99t have checksum integrated, = validation is done by another program - pkg or = another.</div><div><br></div><div><br></div><div><blockquote = type=3D"cite"><div><div><br><br><blockquote type=3D"cite">Why do you = need modify snapshot image ? Could you describe more? Do you<br>modify = current 3 snapshot files?<br></blockquote><br>Analysis that require ram = / nvram modification? Not sure if this is<br>already possible, but may = come handy for experimenting with uefi and<br>maybe some OS (features) = that will not run with unmodified nvram = :-P<br></div></div></blockquote><div><br></div><div><br></div>Sorry I = don=E2=80=99t get, why do you need to modify snapshot image, but not = directly vmem on the = running</div><div>VM?</div><div><br></div><div>Another question, = checksum and modifying image - two mutual exclusive = things. </div><div><br><blockquote = type=3D"cite"><div><div><br><br><blockquote type=3D"cite">If you are = talking about compatibility of a Image format - it should be compatible = in<br>both directions, at least for not so big format changes.<br><br>If = consider overall snapshot/resume compatibility - I believe forward = compatibility<br>is not case and target. Indeed, why do you need = to resume an image created by<br>a higher version of a = program?<br></blockquote><br>This happens quite often. For instance = there is a bug in application<br>and I need to revert to (at least) one = step older version. Then I am<br>unable to work on a file that I just = saved (or was autosaved for me).<br>Firefox profile settings let be the = first example. KiCAD file format<br>is another example (sometimes I need = to switch to a devel build to<br>evade a nasty blocker bug then anyone = else that uses a release is<br>blocked for some months including me = myself).<br></div></div></blockquote><div><br></div><div>Any additional = thing has a cost of development, testing and support. = Current</div><div>Implementation doesn=E2=80=99t support compatibility = at all. Having compatibility in both</div><div>directions can be = hard.</div><div><br></div><div>For example, if some variable is removed = in bhyve, backward compatibility is fine,</div><div>but forward = compatibly is not possible unless that removed variable is being = saved</div><div>into a snapshot image just for forward compatibility. = And of course, it should be tested</div><div>and verified as = worked.</div><div><br></div><div>Do you like that approach? I don=E2=80=99= t think so. So I guess only backward compatibility</div><div>should be = supported to make the snapshot code simple and = robust.</div><div><br></div></div><div>Thanks,</div><div>Vitaliy = Gusev</div><div><br></div><div><br></div></div></blockquote></div><br = clear=3D"all"><br><span class=3D"gmail_signature_prefix">-- = </span><br><div dir=3D"ltr" class=3D"gmail_signature">Mario.<br></div> </div></blockquote></div><br></body></html>= --Apple-Mail=_9EC57A81-2637-440C-A2F4-5E1697C8811A--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?D243949C-4C2E-4C6E-8961-7534DD2CCD00>