Re: [ath9k-devel] [PATCH v2] ath9k: Add support for ITS-G5 band (5.9 GHz)
Hi Jouni, thanks for quick reply. On Mon, Nov 02 2015, Jouni Malinen wrote: > On Mon, Nov 02, 2015 at 11:22:57AM +0100, Michal Sojka wrote: >> The patch adds support for Intelligent Transportation System (ITS-G5) >> band to the ath9k driver. > > NAK. This would enable use of licensed 5.9 GHz band on large number of > deployed "world roaming" cards. I agree that this is not good. > This would allow one to set up an AP on such a channel and would also > make station mode scan those channels with active scan (i.e., sending > Probe Request frames) on them by default for every single full scan. > That's not appropriate regardless of whether > CFG80211_CERTIFICATION_ONUS is set. Can this be solved by having proper/new regulatory flags on these channels that would prohibit running AP or scanning on these channels? > This would be bad from both regulatory enforcement view point (5.9 GHz > band is not allowed for this type of use) and normal use case > performance (adding more channels for scanning makes scans take longer > without there being any point in scanning a band that is not supposed to > have APs for normal station mode connection). > >> in this second version of the patch we removed dependency on >> CFG80211_CERTIFICATION_ONUS as suggested by Johannes. We are, however, >> not sure whether this is the right thing to do. >> >> The problem is that ath9k uses (REGULATORY_STRICT_REG | >> REGULATORY_CUSTOM_REG), which means that in order to use the 5.9 GHz >> band, ath9k's private regdomain has to be extended. This in turn means >> that the 5.9 GHz band is enabled by default in many configurations. It >> can be disabled if one sends a regulatory hint and has valid regdb in >> user space, but this cannot be relied upon. > > This sounds like a special use case and I don't see why upstream Linux > kernel should enable those channels regardless of kernel build > configuration. I expect that there will be quite a lot applications/devices that will need to communicate in this band. From technical point of view, it might be beneficial if there is one solid implementation available in the upstream Linux. I'm not sure about the legal point of view. > Proper regulatory rule enforcement is needed to prevent the channels > from being used in unlicensed use cases. Can you image this "proper regulatory rule enforcement" as a part of upstream Linux? Do you have an idea how it would look like? >> Especially the US regulatory suggests that using >> CFG80211_CERTIFICATION_ONUS might have sense (see the previous version >> http://www.mail-archive.com/linux-wireless@vger.kernel.org/msg15228.html). >> What do you think? > > I don't think it is sufficient to enable these channels based on any > kernel build configuration parameter. We must prevent accidental use of > these channels regardless of what config options a user might pick. Would kernel config option + custom regdb be sufficient? Cheers. -Michal ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
Re: [ath9k-devel] [PATCH v2] ath9k: Add support for ITS-G5 band (5.9 GHz)
On Mon, Nov 02 2015, Jouni Malinen wrote: > On Mon, Nov 02, 2015 at 06:33:45PM +0100, Michal Sojka wrote: >> Can this be solved by having proper/new regulatory flags on these >> channels that would prohibit running AP or scanning on these channels? > > I'm not sure that alone is sufficient, but yes, I think this should be > done as part of the solution. On the 5.9 GHz band, cfg80211 should allow > only the operations modes that are appropriate for that band. We discussed that about a year ago [1]. The thing is that regulatory documents do not talk about modes (at least in Europe). They only talk about channel widths, EIRP etc. and say that the band is designated for Intelligent Transportation System (ITS) applications. Only the ITS standards (e.g. ETSI EN 302 663) talk about OCB mode. From the last year's discussion I took away that we should not restrict these bands to OCB only, because regulatory documents do not require it. But I might get it wrong. [1] http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg656581.html > >> I expect that there will be quite a lot applications/devices that will >> need to communicate in this band. From technical point of view, it might >> be beneficial if there is one solid implementation available in the >> upstream Linux. I'm not sure about the legal point of view. > > I agree that it would be convenient and maybe even beneficial in the end > as long as it is done in a way that meets the requirements for enforcing > rules on the licensed band. > >> Can you image this "proper regulatory rule enforcement" as a part of >> upstream Linux? Do you have an idea how it would look like? > > I'm not sure what would be sufficient. In general, I'm hesitant on > enabling any licensed bands for Wi-Fi operations by default regardless > of what the kernel configuration is. > >> Would kernel config option + custom regdb be sufficient? > > That would certainly be much closer to what I'd like to see from the > regulatory enforcement view point; not sure how convenient this is to > use with ath9k. Hmm, ath9k is the hardware that we can currently play with. Can you suggest another hardware that supports 5.9 GHz and a driver that would be more convenient to develop with? > I think the custom regdb route (i.e., require someone to knowingly > generate the explicit rules to enable the licensed bands and only > distribute the regdb with these changes to properly licensed users) > was one of the approaches discussed in the past for this type of use > cases. Thanks for all the input. We will try to come up with another solution. Regards. -Michal ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
Re: [ath9k-devel] [PATCH v2] ath9k: Add support for ITS-G5 band (5.9 GHz)
On Mon, Nov 02, 2015 at 06:33:45PM +0100, Michal Sojka wrote: > Can this be solved by having proper/new regulatory flags on these > channels that would prohibit running AP or scanning on these channels? I'm not sure that alone is sufficient, but yes, I think this should be done as part of the solution. On the 5.9 GHz band, cfg80211 should allow only the operations modes that are appropriate for that band. > I expect that there will be quite a lot applications/devices that will > need to communicate in this band. From technical point of view, it might > be beneficial if there is one solid implementation available in the > upstream Linux. I'm not sure about the legal point of view. I agree that it would be convenient and maybe even beneficial in the end as long as it is done in a way that meets the requirements for enforcing rules on the licensed band. > Can you image this "proper regulatory rule enforcement" as a part of > upstream Linux? Do you have an idea how it would look like? I'm not sure what would be sufficient. In general, I'm hesitant on enabling any licensed bands for Wi-Fi operations by default regardless of what the kernel configuration is. > Would kernel config option + custom regdb be sufficient? That would certainly be much closer to what I'd like to see from the regulatory enforcement view point; not sure how convenient this is to use with ath9k. I think the custom regdb route (i.e., require someone to knowingly generate the explicit rules to enable the licensed bands and only distribute the regdb with these changes to properly licensed users) was one of the approaches discussed in the past for this type of use cases. -- Jouni MalinenPGP id EFC895FA ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
Re: [ath9k-devel] [PATCH v2] ath9k: Add support for ITS-G5 band (5.9 GHz)
On Mon, Nov 02, 2015 at 07:38:57PM +0100, Michal Sojka wrote: > We discussed that about a year ago [1]. The thing is that regulatory > documents do not talk about modes (at least in Europe). They only talk > about channel widths, EIRP etc. and say that the band is designated for > Intelligent Transportation System (ITS) applications. Only the ITS > standards (e.g. ETSI EN 302 663) talk about OCB mode. From the last > year's discussion I took away that we should not restrict these bands to > OCB only, because regulatory documents do not require it. But I might > get it wrong. > > [1] http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg656581.html In some sense, I agree with that, but taken into account that I'm much more concerned about accidentally using this band, I think there is justification for adding that extra constraint of allowing only the OCB mode to be used even if the regulatory requirements may not explicitly say so. Especially the behavior of including these channels with active scanning allowed in all full scans is something that really must not be enabled. > Hmm, ath9k is the hardware that we can currently play with. Can you > suggest another hardware that supports 5.9 GHz and a driver that would > be more convenient to develop with? I don't think there is any hardware alternative that would be more convenient for this type of efforts than chips supported by ath9k. It is just that the needs of this project are somewhat in conflict with the needs of regulatory rule enforcement for most other use cases.. :) -- Jouni MalinenPGP id EFC895FA ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
Re: [ath9k-devel] [PATCH v2] ath9k: Add support for ITS-G5 band (5.9 GHz)
On Mon, Nov 02, 2015 at 11:22:57AM +0100, Michal Sojka wrote: > The patch adds support for Intelligent Transportation System (ITS-G5) > band to the ath9k driver. NAK. This would enable use of licensed 5.9 GHz band on large number of deployed "world roaming" cards. This would allow one to set up an AP on such a channel and would also make station mode scan those channels with active scan (i.e., sending Probe Request frames) on them by default for every single full scan. That's not appropriate regardless of whether CFG80211_CERTIFICATION_ONUS is set. This would be bad from both regulatory enforcement view point (5.9 GHz band is not allowed for this type of use) and normal use case performance (adding more channels for scanning makes scans take longer without there being any point in scanning a band that is not supposed to have APs for normal station mode connection). > in this second version of the patch we removed dependency on > CFG80211_CERTIFICATION_ONUS as suggested by Johannes. We are, however, > not sure whether this is the right thing to do. > > The problem is that ath9k uses (REGULATORY_STRICT_REG | > REGULATORY_CUSTOM_REG), which means that in order to use the 5.9 GHz > band, ath9k's private regdomain has to be extended. This in turn means > that the 5.9 GHz band is enabled by default in many configurations. It > can be disabled if one sends a regulatory hint and has valid regdb in > user space, but this cannot be relied upon. This sounds like a special use case and I don't see why upstream Linux kernel should enable those channels regardless of kernel build configuration. Proper regulatory rule enforcement is needed to prevent the channels from being used in unlicensed use cases. > Especially the US regulatory suggests that using > CFG80211_CERTIFICATION_ONUS might have sense (see the previous version > http://www.mail-archive.com/linux-wireless@vger.kernel.org/msg15228.html). > What do you think? I don't think it is sufficient to enable these channels based on any kernel build configuration parameter. We must prevent accidental use of these channels regardless of what config options a user might pick. -- Jouni MalinenPGP id EFC895FA ___ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
