Date: Fri, 05 Nov 2004 01:09:23 +0100 From: Willem Jan Withagen <wjw@withagen.nl> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-arch@freebsd.org Subject: Re: Booting questions .... Message-ID: <418AC4B3.9020305@withagen.nl> In-Reply-To: <200411041835.46465.jhb@FreeBSD.org> References: <418AB176.9030604@withagen.nl> <200411041835.46465.jhb@FreeBSD.org>
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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)
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)
test_bytes( char *start, char* end, char mask) {
char *save;
while (start < end ) {
*start = mask;
start++;
}
start = save;
while (start < end ) {
if (*start != mask) error(start);
start++;
}
}
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.
--WjW
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