Hi Serguei,
I'm looking for a working patch for the Linux kernel 2.6.28.8 that would allow using CONFIG_LOGBUFFER (a kernel log buffer shared between U-Boot and the kernel). I'm using u-boot 1.3.3. When LOGBUFFER is enabled in the kernel configuration the kernel build fails with: kernel/built-in.o: In function `setup_ext_logbuff': : undefined reference to `setup_ext_logbuff_mem'
This is to be expected - CONFIG_LOGBUFFER only worked with arch/ppc. It is broken since the arch/ppc removal and nobody (yet) cared to get it to life again. Only recently there were discussions on the linux-embedded ml[1] which may yield other solutions going mainline.
Could anybody also tell me how the buffer location (I think the size is fixed to 16K) is communicated to the kernel, via a kernel command line parameter? If so, what is it?
It was placed at a known address relative to the end of RAM. Check arch/ppc/mm/init.c e.g. in our DENX-v2.6.25-stable branch.
Cheers Detlev
[1] http://www.mail-archive.com/linux-embedded@vger.kernel.org/msg01945.html