On Sat, Mar 05, 2022 at 07:21:15PM +0000, Maciej W. Rozycki wrote: > On Sat, 5 Mar 2022, Mike Rapoport wrote: > > > > > For example I have an x86 system that Linux does not how to interrogate > > > > for RAM beyond 64MiB, so I do use `memmap=128M@0' (for legacy reasons the > > > > x86 platform has a special exception to always exclude area between 640K > > > > and 1M from being used even if not explicitly specified, but we do not > > > > have a need for such legacy such legacy concerns with the MIPS port). I > > > > consider it an interim measure however until the kernel has been fixed. > > > > > > > > Maciej > > > > > > > > > > Hi Mike, Thomas and Maciej, > > > > > > Thank you very much for your feedbacks and discussions. > > > > > > To be frank, I think mem= and memmap= are used for debugging and testing > > > in most cases, the intention of this patchset is to refactor the related > > > code to make them work well on mips. > > > > mem= works fine on mips and there is no need to change it. > > > > If you must supply complex memory layout on the command line, consider > > implementing support for memmap=exact and multiple memmap= parameters on > > the kernel command line, like x86 does. > > There's nothing to implement as the MIPS port has supported arbitrary > memory maps since Dec 11th, 2000; that's almost 22 years now. C.f.: > <https://lore.kernel.org/linux-mips/Pine.GSO.3.96.1000814133957.7256S-100000@xxxxxxxxxxxxxxxxxxx/>, > <https://git.kernel.org/pub/scm/linux/kernel/git/ralf/linux.git/commit/?id=97b7ae4257ef>. You are right, and providing mem=X@Y for each contiguous memory range should work even after 22 years. I missed the fact that mem= can be repeated several times. > Sadly commit a09fc446fb6d ("[MIPS] setup.c: use early_param() for early > command line parsing") removed last pieces of inline documentation; I > don't know why things like that get approved, but neither I can take > responsibility. This is sad indeed, but we still can update the kernel-parameters.txt with a MIPS paragraph. > Maciej -- Sincerely yours, Mike.
