Re: FAQ: MILO gets memory size wrong
On Tue, 18 Aug 1998 Jay.Estabrook@digital.com wrote:
>
> >>> Wojtek Puchar said:
> >
> > MILO detects only 24MB of RAM (I have 2x32MB RAM)
> >
> > I boot MILO from SRM console.
> >
> > I will try using aboot...
>
> There are two ways in which the LINUX kernel will have accurate information
> about how much memory is installed in the box:
>
> 1. boot the kernel *DIRECTLY* from SRM console (via aboot).
I will use aboot, after i repair my machine.
I dont want to have ARC, because i dont need nice menus and
booting Windoze
>
> 2. boot the kernel via MILO from ARC or AlphaBIOS console.
>
> The LINUX kernel expects an array of "memory descriptors" to be pointed to
> by the HWRPB (see the Alpha Architecture Reference Manual for details on
> what the HWRPB is, and what the memory descriptors look like).
>
> These "descriptors" describe the use of main memory pages (basically "free"
> or "occupied").
>
> #1 works because the SRM console sets up the HWRPB and "memory descriptors",
> while reserving some memory for itself, the HWRPB, and PALcode.
>
> #2 works because "linload.exe" passes along to MILO memory size information,
> that it itself gets from ARC or AlphaBIOS. MILO then builds the appropriate
> "memory descriptors" for the amount of memory it has been told, also keeping
> some pages for itself, PALcode, HWRPB.
>
> So, if you boot MILO from SRM console, MILO gets *NO* information about the
> size of memory; in this case, which it fortunately detects, it chooses a
> default size (24 for NONAME/UDB, 32 for the others, IIRC), and builds the
> "memory descriptors" for that size.
>
> Using "set MEMORY_SIZE 64", or some such, will work, as MILO will re-do the
> memory descriptors appropriately. But it's not the correct solution, IMHO.
>
> Remember, on many ALpha platforms, kernels built to boot from SRM will *not*
> boot from MILO, and vice versa. Fortunately, I believe NONAME/UDB is one of
> those platforms whose kernels will boot from either... ;-}
>
> --Jay++
>
> -------------------------------------------------------------------------------
> American Non Sequitur Society: we don't make sense, but we do like pizza...
>
> Jay A Estabrook Alpha Motherboards - LINUX Project
> Digital Equipment Corp. (508) 841-3241 or (DTN) 237-3241
> 334 South Street, Shrewsbury, MA 01545 Jay.Estabrook@digital.com
> -------------------------------------------------------------------------------
>
>
>
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