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NFP is entirely programmable, including the PCI data interface. Using a fixed control BAR layout certainly makes implementations easier, but require careful considerations when space is allocated. Once BAR area is allocated to one feature nothing else can use it. Allocating space statically also requires it to be sized upfront, which leads to either unnecessary limitation or wastage. We currently have a 32bit capability word defined which tells drivers which application FW features are supported. Most of the bits are exhausted. The same bits are also reused for enabling specific features. Bulk of capabilities don't have a need for an enable bit, however, leading to confusion and wastage. TLVs seems like a better fit for expressing capabilities of applications running on programmable hardware. This patch leaves the front of the BAR as is, and declares a TLV capability start at offset 0x58. Most of the space up to 0x0d90 is already allocated, but the used space can be wrapped with RESERVED TLVs. E.g.: Address Type Length 0x0058 RESERVED 0xe00 /* Wrap basic structures */ 0x0e5c FEATURE_A 0x004 0x0e64 FEATURE_B 0x004 0x0e6c RESERVED 0x990 /* Wrap qeueue stats */ 0x1800 FEATURE_C 0x100 Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.