Hi, I use "-device pci-assign,host=00:1a.0" to forward a USB host chip to a Win7 32 bit inside of qemu/kvm. That used to work pretty well, but it broke horribly somewhere after 4.1. With recent kernels the virtual machine boots, but is _very_ slow. It takes hours to boot. If PCI forwarding is disabled, everything is fine. qemu throws this warning on startup: qemu-system-i386: -device pci-assign,host=00:1a.0: PCI region 0 at address 0xf253a000 has size 0x400, which is not a multiple of 4K. You might experience some performance hit due to that. _But_ it also shows that warning for 4.1 and earlier kernels that work pretty fast. I tried to bisect the problem, but I ran into some some kernels that don't even boot on my machine (the skipped ones). So it's a bit hard to make progress. Here is my git bisect log that narrows it down to under 100 commits. Does anyone have a clue what could cause this? (The log can be replayed with git bisect replay on Linus' tree). # bad: [8005c49d9aea74d382f474ce11afbbc7d7130bec] Linux 4.4-rc1 # good: [b953c0d234bc72e8489d3bf51a276c5c4ec85345] Linux 4.1 git bisect start 'v4.4-rc1' 'v4.1' # bad: [dd5cdb48edfd34401799056a9acf61078d773f90] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next git bisect bad dd5cdb48edfd34401799056a9acf61078d773f90 # bad: [23908db413eccd77084b09c9b0a4451dfb0524c0] Merge tag 'staging-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging git bisect bad 23908db413eccd77084b09c9b0a4451dfb0524c0 # bad: [14738e03312ff1137109d68bcbf103c738af0f4a] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input git bisect bad 14738e03312ff1137109d68bcbf103c738af0f4a # good: [5a602e157a9d91d5ce98d07c404097edba8ec9f3] Merge tag 'spi-v4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi git bisect good 5a602e157a9d91d5ce98d07c404097edba8ec9f3 # good: [a4244b0cf58d56c171874e85228ba5deffeb017a] net/ethtool: Add current supported tunable options git bisect good a4244b0cf58d56c171874e85228ba5deffeb017a # bad: [98ec21a01896751b673b6c731ca8881daa8b2c6d] Merge branch 'sched-hrtimers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect bad 98ec21a01896751b673b6c731ca8881daa8b2c6d # good: [4b1f2af6752a4cc9acc1c22ddf3842478965f113] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux git bisect good 4b1f2af6752a4cc9acc1c22ddf3842478965f113 # good: [08d183e3c1f650b4db1d07d764502116861542fa] Merge tag 'powerpc-4.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux git bisect good 08d183e3c1f650b4db1d07d764502116861542fa # skip: [05fe125fa3237de2ec5bada80031e694de78909c] Merge tag 'kvm-arm-for-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD git bisect skip 05fe125fa3237de2ec5bada80031e694de78909c # skip: [edc90b7dc4ceef62ef0ad9cc6c3f5dc770e83ad2] KVM: MMU: fix SMAP virtualization git bisect skip edc90b7dc4ceef62ef0ad9cc6c3f5dc770e83ad2 # skip: [910a6aae4e2e45855efc4a268e43eed2d8445575] KVM: MTRR: exactly define the size of variable MTRRs git bisect skip 910a6aae4e2e45855efc4a268e43eed2d8445575 # skip: [822bf4833ecc8ea63c69f3ed894c13b4509c9e85] arm64: defconfig: enable memtest git bisect skip 822bf4833ecc8ea63c69f3ed894c13b4509c9e85 -- Michael
Attachment:
pgpSaISb57FWx.pgp
Description: OpenPGP digital signature
