Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host
Dear Arnd Please excuse my late response. On Sat, 22 Feb 2020 22:31:40 +0100 Arnd Bergmann wrote: > On Sat, Feb 22, 2020 at 3:40 PM Takashi Yoshi > wrote: > > On Monday, 10.02.2020, 14:13 + Marc Zyngier wrote: > > > KVM/arm was merged just over 7 years ago, and has lived a very > > > quiet life so far. It mostly works if you're prepared to deal > > > with its limitations, it has been a good prototype for the arm64 > > > version, but it suffers a few problems: > > > > > > - It is incomplete (no debug support, no PMU) > > > - It hasn't followed any of the architectural evolutions > > > - It has zero users (I don't count myself here) > > > > I might not be an important user, but I have been for multiple years > > and still am a regular user of KVM/arm32 on different devices. > > > > I use KVM on my Tegra K1 Chromebook for app development and have > > multiple SBCs at home on which I run VMs on using KVM+libvirt. > > > > Sure, neither of these devices has many resources available, but > > they are working fine. I would love to keep them in service since I > > haven't found arm64-based replacements that don't require hours > > upon hours of tinkering to just get a basic OS installation running > > with a mainline kernel. > > > > As an example that they can still be of use in 2020 I'd like to > > point out that one of the SBCs is running my DNS resolver, LDAP > > server, RSS reader, IRC bouncer, and shared todo list just fine, > > each in their separate VM. > > Thank you for providing an important data point to this question. > > > > - It is more and more getting in the way of new arm64 developments > > > > > > So here it is: unless someone screams and shows that they rely on > > > KVM/arm to be maintained upsteam, I'll remove 32bit host support > > > form the tree. > > > > *scream* > > > > > One of the reasons that makes me confident nobody is > > > using it is that I never receive *any* bug report. Yes, it is > > > perfect. > > > > This assumption is deeply flawed. Most users (including me) are not > > subscribed to this mailing list and will never find this thread at > > all. I myself stumbled upon this discussion just by chance while I > > was browsing the web trying to find something completely unrelated. > > > > I've been using KVM on x86, ppc and arm for many years, yet I never > > felt the need to report a bug on the mailing list. > > (This is to be interpreted as a compliment to the great work the > > devs of KVM have done!) > > > > Just going by the number of bugs reported on a developers mailing > > list is not going to paint an accurate picture. > > > > I am convinced that I'm not the only one relying on KVM/arm32 in the > > mainline kernel and would ask you to please reconsider keeping > > arm32 in the mainline kernel for a few more years until adequate > > arm64 replacements are available on the market and have gained > > proper support in the mainline kernel. > > Can you provide some more information about how you use KVM on 32-bit > machines, to make it possible to better estimate how many others might > do the same, Sure. First of all I own different ARM boards. Currently I virtualise on Banana Pi M1 (1GB), cubox-i (2GB) and my Acer Chromebook (4GB). The Chromebook is my travel laptop on which I have three VMs on (LAMP, PostgreSQL, kernel testing) which I primarily use to develop against. The others are "home servers", they run all kinds of things for my home (incl. DNS, LDAP, RSS-Reader, Wiki, Music-Database, RDBMS, Task-Management). > and how long you will need to upgrade to newer kernels for? I don't really have a strict policy regarding when to upgrade kernels. I just run whatever gets patched and works. Sometimes this is the latest stable release, most of the time this is the last longterm release. > In particular: > > - What is the smallest amount of physical RAM that you have to found > to make a usable ARM/KVM host? Not sure if I can answer this question adequately as the smallest of my ARM32 boards have at least 1GB of RAM, which works for sure. Since you're asking about the smallest amount I did some experiments. I spun up the testing VM on my Chromebook. It consists of a basic Gentoo userland currently running on a "reduced" 4.19 kernel (I'm sure it could be stripped further if one was determined enough). When I boot it up and log in the qemu-system process on the host uses 100MB. The memory usage (incl. cache) inside the VM is only 50 MB, though. Adding a few M
Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host
Hi I found this mailing list thread and would like to express my opinion and dependence on KVM/arm32. I hope that I'm not too late already. On Monday, 10.02.2020, 14:13 + Marc Zyngier wrote: > KVM/arm was merged just over 7 years ago, and has lived a very quiet > life so far. It mostly works if you're prepared to deal with its > limitations, it has been a good prototype for the arm64 version, > but it suffers a few problems: > > - It is incomplete (no debug support, no PMU) > - It hasn't followed any of the architectural evolutions > - It has zero users (I don't count myself here) I might not be an important user, but I have been for multiple years and still am a regular user of KVM/arm32 on different devices. I use KVM on my Tegra K1 Chromebook for app development and have multiple SBCs at home on which I run VMs on using KVM+libvirt. Sure, neither of these devices has many resources available, but they are working fine. I would love to keep them in service since I haven't found arm64-based replacements that don't require hours upon hours of tinkering to just get a basic OS installation running with a mainline kernel. As an example that they can still be of use in 2020 I'd like to point out that one of the SBCs is running my DNS resolver, LDAP server, RSS reader, IRC bouncer, and shared todo list just fine, each in their separate VM. > - It is more and more getting in the way of new arm64 developments > > So here it is: unless someone screams and shows that they rely on > KVM/arm to be maintained upsteam, I'll remove 32bit host support > form the tree. *scream* > One of the reasons that makes me confident nobody is > using it is that I never receive *any* bug report. Yes, it is > perfect. This assumption is deeply flawed. Most users (including me) are not subscribed to this mailing list and will never find this thread at all. I myself stumbled upon this discussion just by chance while I was browsing the web trying to find something completely unrelated. I've been using KVM on x86, ppc and arm for many years, yet I never felt the need to report a bug on the mailing list. (This is to be interpreted as a compliment to the great work the devs of KVM have done!) Just going by the number of bugs reported on a developers mailing list is not going to paint an accurate picture. I am convinced that I'm not the only one relying on KVM/arm32 in the mainline kernel and would ask you to please reconsider keeping arm32 in the mainline kernel for a few more years until adequate arm64 replacements are available on the market and have gained proper support in the mainline kernel. I myself unfortunately do neither have the knowledge nor resources to help with development in KVM or maintaining a non-mainline kernel. > But if you depend on KVM/arm being available in mainline, please > shout. > > To reiterate: 32bit guest support for arm64 stays, of course. Only > 32bit host goes. Once this is merged, I plan to move virt/kvm/arm to > arm64, and cleanup all the now unnecessary abstractions. > > The patches have been generated with the -D option to avoid spamming > everyone with huge diffs, and there is a kvm-arm/goodbye branch in > my kernel.org repository. > > [...] Thanks for your understanding. Kind regards - Yoshi ___ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host
Hi I found this mailing list thread and would like to express my opinion and dependence on KVM/arm32. I hope that I'm not too late already. On Monday, 10.02.2020, 14:13 + Marc Zyngier wrote: > KVM/arm was merged just over 7 years ago, and has lived a very quiet > life so far. It mostly works if you're prepared to deal with its > limitations, it has been a good prototype for the arm64 version, > but it suffers a few problems: > > - It is incomplete (no debug support, no PMU) > - It hasn't followed any of the architectural evolutions > - It has zero users (I don't count myself here) I might not be an important user, but I have been for multiple years and still am a regular user of KVM/arm32 on different devices. I use KVM on my Tegra K1 Chromebook for app development and have multiple SBCs at home on which I run VMs on using KVM+libvirt. Sure, neither of these devices has many resources available, but they are working fine. I would love to keep them in service since I haven't found arm64-based replacements that don't require hours upon hours of tinkering to just get a basic OS installation running with a mainline kernel. As an example that they can still be of use in 2020 I'd like to point out that one of the SBCs is running my DNS resolver, LDAP server, RSS reader, IRC bouncer, and shared todo list just fine, each in their separate VM. > - It is more and more getting in the way of new arm64 developments > > So here it is: unless someone screams and shows that they rely on > KVM/arm to be maintained upsteam, I'll remove 32bit host support > form the tree. *scream* > One of the reasons that makes me confident nobody is > using it is that I never receive *any* bug report. Yes, it is > perfect. This assumption is deeply flawed. Most users (including me) are not subscribed to this mailing list and will never find this thread at all. I myself stumbled upon this discussion just by chance while I was browsing the web trying to find something completely unrelated. I've been using KVM on x86, ppc and arm for many years, yet I never felt the need to report a bug on the mailing list. (This is to be interpreted as a compliment to the great work the devs of KVM have done!) Just going by the number of bugs reported on a developers mailing list is not going to paint an accurate picture. I am convinced that I'm not the only one relying on KVM/arm32 in the mainline kernel and would ask you to please reconsider keeping arm32 in the mainline kernel for a few more years until adequate arm64 replacements are available on the market and have gained proper support in the mainline kernel. I myself unfortunately do neither have the knowledge nor resources to help with development in KVM or maintaining a non-mainline kernel. > But if you depend on KVM/arm being available in mainline, please > shout. > > To reiterate: 32bit guest support for arm64 stays, of course. Only > 32bit host goes. Once this is merged, I plan to move virt/kvm/arm to > arm64, and cleanup all the now unnecessary abstractions. > > The patches have been generated with the -D option to avoid spamming > everyone with huge diffs, and there is a kvm-arm/goodbye branch in > my kernel.org repository. > > [...] Thanks for your understanding. Kind regards - Yoshi HiI found this mailing list thread and would like to express my opinion and dependence on KVM/arm32.I hope that I'm not too late already.On Monday, 10.02.2020, 14:13 + Marc Zyngier wrote:> KVM/arm was merged just over 7 years ago, and has lived a very quiet> life so far. It mostly works if you're prepared to deal with its> limitations, it has been a good prototype for the arm64 version,> but it suffers a few problems:> > - It is incomplete (no debug support, no PMU)> - It hasn't followed any of the architectural evolutions> - It has zero users (I don't count myself here)I might not be an important user, but I have been for multiple years and still am a regular user of KVM/arm32 on different devices.I use KVM on my Tegra K1 Chromebook for app development and have multiple SBCs at home on which I run VMs on using KVM+libvirt.Sure, neither of these devices has many resources available, but they are working fine. I would love to keep them in service since I haven't found arm64-based replacements that don't require hours upon hours of tinkering to just get a basic OS installation running with a mainline kernel.As an example that they can still be of use in 2020 I'd like to point out that one of the SBCs is running my DNS resolver, LDAP server, RSS reader, IRC bouncer, and shared todo list just fine, each in their separate VM.> - It is more and more getting in the way of new arm64 developments> > So here it is: unless someone screams and shows that they rely on> KVM/arm to be maintained upsteam, I'll remove 32bit host support> form the tree.*scream*> One of the reasons that makes me confident nobody is> using it is that I never receive *any* bug report. Yes, it is> perfect.This assumptio
