Date: Fri, 5 Nov 2004 14:00:34 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Willem Jan Withagen <wjw@withagen.nl> Cc: freebsd-arch@FreeBSD.org Subject: Re: Booting questions .... Message-ID: <200411051400.34684.jhb@FreeBSD.org> In-Reply-To: <418AC4B3.9020305@withagen.nl> References: <418AB176.9030604@withagen.nl> <200411041835.46465.jhb@FreeBSD.org> <418AC4B3.9020305@withagen.nl>
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On Thursday 04 November 2004 07:09 pm, Willem Jan Withagen wrote: > John Baldwin wrote: > > On Thursday 04 November 2004 05:47 pm, Willem Jan Withagen wrote: > >>Hi, > >> > >>I'm looking for a place to sensibly insert memorytest routines.... > >> > >>Currently I'd like to do that not in the loader, but in the kernel where > >>memory is already setup to be one flat address space. This makes > >>programming a lot simpler. > > > > The loader does use a flat address space, it is just rooted at 0xa000 > > rather than 0x0, so you can't test the first few kb FWIW. > > Nice, > > But is it unsegmented? (perhaps I have a wrong idea of a flat address > space) Yes, it is unsegmented. You can translate physical addresses to virtual addresses using PTOV() and vice versa using VTOP(). > What I mean with this is that I can iterate from 0xa000 to 0xffffffff with > a "char *p" and do test_bytes( 0xa000, 0xffffffff, 0xff). (assuming this > all has memory) Yes. > Next is then which ranges are valid to test, and then things really start > to get complicated and arch dependant. Which is why I ended up in machdep.c > right after the setting up of the memory ranges. Heh, the above memory mapping is also i386 specific. Alpha only has a small bit of memory mapped in the loader, same with sparc64, etc. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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