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![]() When rules are inserted into the A-TCAM they are associated with a mask, which is part of the lookup key: { masked key, mask ID, region ID }. These masks are called rule patterns (RP) and the aggregation of several masks into one (to be introduced in follow-up patch sets) is called an extended RP (eRP). When a packet undergoes a lookup in an ACL region it is masked by the current set of eRPs used by the region, looking for an exact match. Eventually, the rule with the highest priority is picked. These eRPs are stored in several global banks to allow for lookup to occur using several eRPs simultaneously. At first, an ACL region will only require a single mask - upon the insertion of the first rule. In this case, the region can use the "master RP" which is composed by OR-ing all the masks used by the region. This mask is a property of the region and thus there is no need to use the above mentioned banks. At some point, a second mask will be needed. In this case, the region will need to allocate an eRP table from the above mentioned banks and insert its masks there. >From now on, upon lookup, the eRP table used by the region will be fetched from the eRP banks - using {eRP bank, Index within the bank} - and the eRPs present in the table will be used to mask the packet. Note that masks with consecutive indexes are inserted into consecutive banks. When rules are deleted and a region only needs a single mask once again it can free its eRP table and use the master RP. The above logic is implemented in the eRP core and represented using the following state machine: +------------+ create mask - as master RP +---------------+ | +--------------------------------> | | no masks | | single mask | | <--------------------------------+ | +------------+ delete mask +-----+--^------+ | | | | create mask - | | delete mask - create mask transition to use eRP | | transition to +--------+ table | | use master RP | | | | | | | | +----v--------+----+ create mask +----v--+-----+ | <-------------------------------+ | | multiple masks | | two masks | | +-------------------------------> | +------------------+ delete mask - if two +-------------+ remaining The code that actually configures rules in the A-TCAM will interface with the eRP core by getting or putting an eRP based on the required mask used by the rule. Signed-off-by: Ido Schimmel <idosch@mellanox.com> Reviewed-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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README |
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.