RFC Add support for a fake, para-virtualised machine
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- v1 RFC Latest1 of 2 patches 0 repliesNew
1 of 2 patches is in this archive. The cover letter announces 2.
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 2/2 | ARM: SMP support for mach-virt | +0 | 21 replies |
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Cover letter [RFC PATCH 0/2] Add support for a fake, para-virtualised machine
Quoted 13 lines · Will Deacon
Hello,
When running Linux on a para-virtualised platform (that is, one where the guest is aware that it is dealing with virtual devices sitting on things like virtio or xenbus) we require very little in the way of platform code and piggy-backing on top of an existing platform can require a lot of device emulation for very little gain.
These two patches introduce mach-virt: a very simple, DT-based machine which can be used with kvmtool in conjunction with virtio-based devices. It's not hard to imagine the same machine being targetted by Xen, which currently emulates a minimal variant of the vexpress platform.
Quoted 7 lines
Note that this patch series depends on the timer rework from Mark Rutland, posted on Friday:
http://lists.infradead.org/pipermail/linux-arm-kernel/2012-November/135651.html
All feedback welcome. We suspect that most controversy will be around the name of the thing :)
We've discussed this before at conferences. I don't know that we concluded this wasn't needed, but it certainly leaned that direction. So what has changed? You're not going to save code space because we're building multiple platforms together. You'll save some boot time, but a stripped down dtb with only the minimal peripherals would probably save nearly as much time. However, I do have concerns with using VExpress as the guest. For example, you can't support a non-PAE guest with 4GB of RAM on VExpress (maybe if the vexpress code gets all memory map info from DT).
Is this really complete? Will we need reset, poweroff, hotplug, and suspend/resume support for example? Unlike most initial platform submissions which are minimal, I think seeing full support would be useful here. Then we can better gauge how much we are really saving.
Rob
Quoted 22 lines
Will
Marc Zyngier (2):
ARM: Dummy Virtual Machine platform support
ARM: SMP support for mach-virtarch/arm/Kconfig | 2 + arch/arm/Makefile | 1 + arch/arm/mach-virt/Kconfig | 9 ++ arch/arm/mach-virt/Makefile | 6 ++ arch/arm/mach-virt/headsmp.S | 38 ++++++++ arch/arm/mach-virt/platsmp.c | 205 +++++++++++++++++++++++++++++++++++++++++++ arch/arm/mach-virt/virt.c | 71 +++++++++++++++ 7 files changed, 332 insertions(+) create mode 100644 arch/arm/mach-virt/Kconfig create mode 100644 arch/arm/mach-virt/Makefile create mode 100644 arch/arm/mach-virt/headsmp.S create mode 100644 arch/arm/mach-virt/platsmp.c create mode 100644 arch/arm/mach-virt/virt.c