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Re: [Qemu-devel] pxe boot problems
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] pxe boot problems |
Date: |
Thu, 30 Jan 2014 12:38:28 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131118 Thunderbird/17.0.11 |
On 01/30/14 07:37, Dietmar Maurer wrote:
>> Does it work with TCG?
>
> It simply hangs a bit later if I use TCG, without any output on the console.
Strange. How recent qemu happens this with? The relevant emulation code
(under "ljmp Ev" in "target-i386/translate.c") has been changed as
recently as commit 78261634 (not in any release yet).
> But It works perfectly when I switch back to the pxe-XX.rom files.
>
>> Also, can you try with a NIC model different from the default e1000?
>
> same behavior with e1000, rtl8139, pcnet
These do match my results.
Please allow me to summarize the rest of the thread:
- New builds of iPXE contain funny jmp instructions.
- They are only present in the qemu tree in the efi-*.rom files,
the pxe-*.rom builds date back to much earlier.
- When running the funny jmp instructions in a KVM guest, you either
need "unrestricted_guest" support from the host CPU (check the
"/sys/module/kvm_intel/parameters/unrestricted_guest" file when
kvm-intel.ko is inserted), *or* you need to ask KVM to emulate invalid
guest state, by passing "emulate_invalid_guest_state=1" to
kvm-intel.ko -- check your module options under /etc/modprobe.d.
(Note that you should rebuild the initramfs with dracut if you change
those options.)
- In the latter case (ie. unrestricted_guest==0 &&
emulate_invalid_guest_state==1), you will still run into an emulation
problem on a current RHEL-6 host *later* (a different jmp insn in
the iPXE builds). I filed RHBZ#1059496 for this and posted the
backport last night. Gleb's upstream patches in question are e35b7b9c
and ea79849d.
Laszlo
- [Qemu-devel] pxe boot problems, Dietmar Maurer, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Dietmar Maurer, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Laszlo Ersek, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Laszlo Ersek, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Paolo Bonzini, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Laszlo Ersek, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Paolo Bonzini, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Laszlo Ersek, 2014/01/29
- Re: [Qemu-devel] pxe boot problems, Dietmar Maurer, 2014/01/30
- Re: [Qemu-devel] pxe boot problems,
Laszlo Ersek <=