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Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite
From: |
Chao Peng |
Subject: |
Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite |
Date: |
Tue, 21 Jun 2016 09:23:08 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
> It would be nice to at least see the patches. :)
>
> I think a lightweight q35 platform that can run the usual firmware could
> be acceptable in QEMU.
OK, I will send out v2.
>
> >> 2) this:
> >>
> >>> - it loads guest kernel directly, no BIOS, no bootloader, no realmode
> >>> code;
> >>
> >> ... which is related to Linux-only support. How much does this gain
> >> over a minimal firmware (either SeaBIOS with the fw_cfg DMA interface,
> >> or qboot with cbfs in parallel flash)?
> >
> > We have tried Q35 version (as described above) with both SeaBIOS and qboot.
> > The 'perfect' time with optimized BIOS we have seen is ~15ms, with the
> > additional time in kernel real mode code, the total time overhead comparing
> > to current Linux-aware implementation is more than 40ms. This sounds still
> > a little too much for us.
>
> I guess it is related to real mode decompression code?
Yes, that's the major part.
>
> My main issue is that there are other things that the firmware does.
> Not all of them are necessary (e.g. SMRAM is not needed, most PCI
> devices need not be initialized), but in general we don't like putting
> code in QEMU that modifies the guest state. For example another Intel
> person is adding code to SeaBIOS that initializes the feature control MSR.
>
> I wonder if Linux could run as a multiboot-compliant ELF file, and what
> the performance would be... Multiboot omits the real mode stub.
>
I can look into this. Thanks.
Chao
- [Qemu-devel] [RFC 5/9] acpi: expose acpi_checksum(), (continued)
- [Qemu-devel] [RFC 5/9] acpi: expose acpi_checksum(), Chao Peng, 2016/06/17
- [Qemu-devel] [RFC 4/9] acpi: expose data structurs and functions of BIOS linker loader, Chao Peng, 2016/06/17
- [Qemu-devel] [RFC 8/9] pc: support direct loading protected/long mode kernel, Chao Peng, 2016/06/17
- [Qemu-devel] [RFC 6/9] acpi: patch guest ACPI for pc-lite, Chao Peng, 2016/06/17
- [Qemu-devel] [RFC 9/9] pc: introduce light weight PC board pc-lite, Chao Peng, 2016/06/17
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Paolo Bonzini, 2016/06/17
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Chao Peng, 2016/06/20
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite,
Chao Peng <=
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Michael S. Tsirkin, 2016/06/21
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Chao Peng, 2016/06/23
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Paolo Bonzini, 2016/06/23
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Claudio Fontana, 2016/06/24
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Claudio Fontana, 2016/06/24
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Paolo Bonzini, 2016/06/24
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Claudio Fontana, 2016/06/26
- Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Chao Peng, 2016/06/28
Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Dr. David Alan Gilbert, 2016/06/20
Re: [Qemu-devel] [RFC 0/9] Introduce light weight PC platform pc-lite, Michael S. Tsirkin, 2016/06/18