10/05/2022 17:05, Rahul Lakkireddy: > On Tuesday, May 05/10/22, 2022 at 16:30:59 +0200, Thomas Monjalon wrote: > > 10/05/2022 16:11, Rahul Lakkireddy: > > > On Tuesday, May 05/10/22, 2022 at 11:02:05 +0200, Thomas Monjalon wrote: > > > > 06/05/2022 13:36, Rahul Lakkireddy: > > > > > The Chelsio FW config file contains a list of register=value pairs to > > > > > change configuration of the NIC before firmware is initialized. > > > > > It closely resembles the INI file format. It is mainly used to aid > > > > > in debugging FW initialization failures and to optimally partition > > > > > NIC hardware resources for specific requirements. Partitioning > > > > > generally involves moving resources on unused Physical Functions > > > > > (PFs) to the main PF, like redistributing queues, hardware TCAMs, > > > > > etc., before firmware begins initialization. Once the configuration > > > > > looks good, then the final FW config file is flashed onto the NIC > > > > > using the cxgbtool. The FW config file can then be removed from the > > > > > /lib/firmware/cxgb4/ directory and the FW will begin initializing > > > > > with the flashed FW config file on the NIC from next time onwards. > > > > > > > > > > With this patch, the FW config file is selected in following order. > > > > > > > > > > 1) Check and select FW config file present in /lib/firmware/cxgb4/ > > > > > directory. > > > > > > > > > > 2) Otherwise, check and select FW config file flashed onto the > > > > > NIC. > > > > > > > > > > 3) Otherwise, select the default FW config file embedded within the > > > > > FW binary on the NIC. > > > > > > > > > > Since this is pretty low-level hardware configuration, the users are > > > > > not expected to change this file without expert guidance. So, > > > > > exporting such a low-level configuration via devargs API does not > > > > > feel like the right fit for this specific requirement. > > > > > > > > > > Once FW is up and running with the FW config file, some of the driver > > > > > and FW runtime features can be enabled/disabled via devargs API during > > > > > driver probe. > > > > > > > > > > To summarize, the FW config file is intended to debug FW > > > > > initialization > > > > > failures and/or aid in resources partitioning before FW starts > > > > > initialization. Once the FW is running, the whole or smaller slices > > > > > of these partitioned resources can be further redistributed across > > > > > the multiple physical ports controlled by the same underlying PF. > > > > > > > > Sorry it is not clear to me. > > > > The FW file is used by cxgbtool to flash it, right? > > > > The PMD may use the same FW file for debug diagnostics? > > > > > > > > > There are 2 FW related files in /lib/firmware/cxgb4 directory that > > > can be written into the NIC flash (at different locations in the flash) > > > using cxgbtool: > > > > > > 1) FW config file (t6-config.txt): This file contains register=value > > > pairs to configure some HW registers before initializing FW > > > (t6fw.bin). These register=value pairs are very low level and > > > specific to HW. The FW config file can be used to enable/disable > > > some paths in HW to debug FW initialization issues. Since it > > > can disable some paths in HW, it can also be used to partition > > > and redistribute resources from other unused PFs to main PF, > > > before FW initialization. > > > > > > 2) FW binary (t6fw.bin): This contains the actual FW. This binary also > > > has an embedded "default" FW config file that will be used if no > > > FW config file (t6-config.txt) is present in NIC "flash" or in the > > > "/lib/firmware/cxgb4/" directory. > > > > > > > How is it used by the kernel? > > > > > > > > > > In kernel cxgb4 driver also, we follow the same sequence when > > > initializing FW. If any FW config file (t6-config.txt) is present > > > in "/lib/firmware/cxgb4" directory, then it is picked up first. > > > Otherwise, a FW config file that has been "flashed" onto the NIC > > > using cxgbtool, is picked up next. Otherwise, FW will init with > > > the "default" FW config file embedded inside the FW binary (t6fw.bin). > > > > > > Currently, the DPDK cxgbe PMD only picks up the FW config file from > > > NIC "flash" or the "default" one inside the FW binary. This patch adds > > > a way to pick FW config file from "lib/firmware/cxgb4" directory when > > > a FW config file is placed there. > > > > OK, so both Linux and DPDK drivers read the FW config file > > to provide better diagnostics. Am I right? > > > > Yes, both use the FW config file to enable/disable specific paths in > HW to get better diagnostics for FW init failures.
OK thanks for the explanation. The idea looks OK.
