Hi Wolfgang, On 20 September 2017 at 13:55, Wolfgang Denk <w...@denx.de> wrote: > Dear Simon, > > sorry for jumping in so late... > > In message <20170916212331.170463-1-...@chromium.org> you wrote: >> >> At present U-Boot has a logbuffer feature which records output in a memory >> buffer for later display or storage. This is useful but is not at present >> enabled for any board. > > Background explanation: When this was implemented, the buffer > handling was fully compatible with the Linux kernel logbuffer. > And U-Boot was able to reserve memory (at the top of the RAM) that > could be shared between U-Boot and Linux, so you could for example > write U-Boot POST results into the log buffer, and read it using > standard syslog tools in Linux. Or keep the panic messages of the > previous crash and read it after reboot. > > IIRC this was in production use only on Power architectre systems, > and it broke (and nover got fixed) when the Linux log buffer was > reworked.
OK I see, i did not realise the Linux connection. > >> This series introduced a new logging system which supports: >> - various log levels from panic to debug >> - log categories including all uclasses and a few others >> - log drivers to which all log records can be sent >> - log filters which control which log records make it to which drivers > > You don't mention it here, but would it be possible to keep > compatibility with the Linux logbuffer implementation in mind? > > So we could re-implement this shared logbuffer thingy in case > someone finds it useful? I think it would be fairly easy to do, yes. It just needs a driver which writes log records into memory at a given address. I certainly don't like removing useful features, will take a look. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
