Re: [Qemu-devel] [PATCH v3 0/7] Improvements and clean-ups related to -net
On 2018年02月21日 18:18, Thomas Huth wrote: "-net" is a legacy option that often causes confusion and misconfigurations for the users, since most people are not aware of the underlying "vlan" (i.e. hub) concept that is used for this parameter. The prefered way of configuring your network stack is to use "--netdev" instead, which gives you a clean 1:1 connection between your emulated guest hardware and the host network backend. However, there are two reasons why we could not completely deprecate "-net" yet: 1) Convenience: In some cases, it's more convenient to use "-net" instead of "--netdev", e.g. if you just want to have a "tap" network connection, it's faster to type "-net nic -net tap" instead of "--device e1000,netdev=n1 --netdev tap,id=n1". 2) On-board NICs: Currently the "-net nic" parameter is the only way to configure on- board NICs on certain (embedded) machines via the nd_table[] array. So beside some generic clean-ups and removal of code that has been marked as deprecated since QEMU 2.10 already, this patch series intro- duces a new parameter "--nic" (in patch 7) which should be able to re- place "-net" in the long run completely: This new convenience parameter can be used to configure the default/on-board guest HW together with a host network backend in a very compact way. To configure a tap backend for the default NIC, you just have to type "--nic tap" here for example. Note that "-net" itself is not marked as deprecated yet - that is subject to a later patch, since it likely needs some additional discussion first (or we might rather want to wait for some more releases first until --nic has been properly established instead)... v3: - Changed the comments in qapi/net.json in patch 5/7 according to the suggestion from Eric. Dropped the Reviewed-bys from this patch since the text changed a bit now. - Dropped the final patch 8 with the updates to qemu-doc about making -net less prominent. I'll resubmit that patch together with a patch that deprecates "-net" in a separate patch series instead (which will likely both need some more discussion first). v2: - Renamed "-n" to "--nic" (suggested by Paolo) - Improved the QAPI comment about the removal of 'dump (suggested by Eric) - exit(0) instead of exit(1) after showing the "-netdev help" (Eric) - Improved the documenation for hubport a little bit (suggested by Paolo) Thomas Huth (7): net: Move error reporting from net_init_client/netdev to the calling site net: List available netdevs with "-netdev help" net: Only show vhost-user in the help text if CONFIG_POSIX is defined net: Make net_client_init() static net: Remove the deprecated way of dumping network packets net: Remove the deprecated 'host_net_add' and 'host_net_remove' HMP commands net: Add a new convenience option "--nic" to configure default/on-board NICs hmp-commands.hx | 30 -- hmp.h | 3 - include/net/net.h | 4 +- include/sysemu/sysemu.h | 1 + monitor.c | 61 net/dump.c | 102 + net/net.c | 239 +++- qapi/net.json | 29 ++ qemu-doc.texi | 16 qemu-options.hx | 48 +++--- tests/test-hmp.c| 2 - vl.c| 10 +- 12 files changed, 170 insertions(+), 375 deletions(-) Applied. Thanks
Re: [Qemu-devel] [PATCH v3 0/7] Improvements and clean-ups related to -net
On 21/02/2018 11:41, Mark Cave-Ayland wrote: > 1) Does the new -nic syntax support multiple on-board NICs? I remember > seeing this on some of the ARM boards I was studying when trying to > implement something similar for SPARC. Yes, but they will be in different subnets if you do "-nic user -nic user". If you want to put them on the same trunk, what you want is (cut-and-pasted from an offlist email from Thomas): -netdev user,id=slirp \ -netdev hubport,id=port,netdev=slirp,hubid=0 \ -nic hubport,hubid=0 \ -nic hubport,hubid=0 We could make id and hubid optional (id was already optional in -net so the logic is there already, see assign_name in net/net.c), giving the much nicer: -netdev user,id=slirp \ -netdev hubport,netdev=slirp \ -nic hubport \ -nic hubport Thanks, Paolo > 2) Is it possible to provide a convenient wrapper function to handle the > logic related to determining whether a specified NIC is on-board or not?
Re: [Qemu-devel] [PATCH v3 0/7] Improvements and clean-ups related to -net
On 21.02.2018 11:41, Mark Cave-Ayland wrote: > On 21/02/18 10:18, Thomas Huth wrote: > >> "-net" is a legacy option that often causes confusion and >> misconfigurations for the users, since most people are not aware >> of the underlying "vlan" (i.e. hub) concept that is used for this >> parameter. The prefered way of configuring your network stack is >> to use "--netdev" instead, which gives you a clean 1:1 connection >> between your emulated guest hardware and the host network backend. >> >> However, there are two reasons why we could not completely deprecate >> "-net" yet: >> >> 1) Convenience: >> In some cases, it's more convenient to use "-net" instead of "--netdev", >> e.g. if you just want to have a "tap" network connection, it's faster >> to type "-net nic -net tap" instead of "--device e1000,netdev=n1 >> --netdev tap,id=n1". >> >> 2) On-board NICs: >> Currently the "-net nic" parameter is the only way to configure on- >> board NICs on certain (embedded) machines via the nd_table[] array. >> >> So beside some generic clean-ups and removal of code that has been >> marked as deprecated since QEMU 2.10 already, this patch series intro- >> duces a new parameter "--nic" (in patch 7) which should be able to re- >> place "-net" in the long run completely: This new convenience parameter >> can be used to configure the default/on-board guest HW together with a >> host network backend in a very compact way. To configure a tap backend >> for the default NIC, you just have to type "--nic tap" here for example. > > Hi Thomas, > > This is a great improvement for configuring on-board NICs! I do have a > couple of questions about your patchset based on personal experience: > > 1) Does the new -nic syntax support multiple on-board NICs? I remember > seeing this on some of the ARM boards I was studying when trying to > implement something similar for SPARC. Yes, that's possible. If you specify the "--nic" parameter multiple times, it populates multiple entries in the nd_table[] array, so boards can pick up multiple NICs from there. For example hw/arm/xlnx-zynqmp.c initializes up to 4 (XLNX_ZYNQMP_NUM_GEMS) on-board NICs this way. > 2) Is it possible to provide a convenient wrapper function to handle the > logic related to determining whether a specified NIC is on-board or not? > > For example take a look at > https://git.qemu.org/?p=qemu.git;a=blob;f=hw/sparc64/sun4u.c;h=da28ab9413efdbe0bf0e1d3bf2b545577b83d88a;hb=a6e0344fa0e09413324835ae122c4cadd7890231#l596 > where we have a nice dance to check whether the device specified is > on-board or not, and if it isn't to plug it in as an extra PCI device > instead. The complication here is that nd_tables[] is populated by > default (and also with -net nic -net user) but not when someone > specifies a single card via -netdev. > > From memory this was derived from the code in > https://git.qemu.org/?p=qemu.git;a=blob;f=hw/arm/realview.c;h=87cd1e583cd20b6d8a2beeef1cba6977496d4477;hb=a6e0344fa0e09413324835ae122c4cadd7890231#l259 > if having another example helps? Do you have something in mind how the interface to such a function should look like? Not sure whether there is a easy, magic solution for all boards ... there are multiple problems, e.g. that you can normally not specify on-board NICs via --device yet... Anyway, that would be subject to another clean-up patch series - this series here only focuses on the net/* files, not on the files in the hw/ folder. Thomas
Re: [Qemu-devel] [PATCH v3 0/7] Improvements and clean-ups related to -net
On 21/02/18 10:18, Thomas Huth wrote: "-net" is a legacy option that often causes confusion and misconfigurations for the users, since most people are not aware of the underlying "vlan" (i.e. hub) concept that is used for this parameter. The prefered way of configuring your network stack is to use "--netdev" instead, which gives you a clean 1:1 connection between your emulated guest hardware and the host network backend. However, there are two reasons why we could not completely deprecate "-net" yet: 1) Convenience: In some cases, it's more convenient to use "-net" instead of "--netdev", e.g. if you just want to have a "tap" network connection, it's faster to type "-net nic -net tap" instead of "--device e1000,netdev=n1 --netdev tap,id=n1". 2) On-board NICs: Currently the "-net nic" parameter is the only way to configure on- board NICs on certain (embedded) machines via the nd_table[] array. So beside some generic clean-ups and removal of code that has been marked as deprecated since QEMU 2.10 already, this patch series intro- duces a new parameter "--nic" (in patch 7) which should be able to re- place "-net" in the long run completely: This new convenience parameter can be used to configure the default/on-board guest HW together with a host network backend in a very compact way. To configure a tap backend for the default NIC, you just have to type "--nic tap" here for example. Hi Thomas, This is a great improvement for configuring on-board NICs! I do have a couple of questions about your patchset based on personal experience: 1) Does the new -nic syntax support multiple on-board NICs? I remember seeing this on some of the ARM boards I was studying when trying to implement something similar for SPARC. 2) Is it possible to provide a convenient wrapper function to handle the logic related to determining whether a specified NIC is on-board or not? For example take a look at https://git.qemu.org/?p=qemu.git;a=blob;f=hw/sparc64/sun4u.c;h=da28ab9413efdbe0bf0e1d3bf2b545577b83d88a;hb=a6e0344fa0e09413324835ae122c4cadd7890231#l596 where we have a nice dance to check whether the device specified is on-board or not, and if it isn't to plug it in as an extra PCI device instead. The complication here is that nd_tables[] is populated by default (and also with -net nic -net user) but not when someone specifies a single card via -netdev. From memory this was derived from the code in https://git.qemu.org/?p=qemu.git;a=blob;f=hw/arm/realview.c;h=87cd1e583cd20b6d8a2beeef1cba6977496d4477;hb=a6e0344fa0e09413324835ae122c4cadd7890231#l259 if having another example helps? ATB, Mark.
