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SubjectRe: holes for ISA boards...
On Sun, Jun 13, 1999 at 04:11:54AM -0000, Christer Weinigel wrote:
% Mark Jefferys <mjeffery@europa.com> wrote:

% >But this part of the patch looks bad to me anyway; it stops anyone from
% >mapping part of the hole to VM, but presumably anything that does this
% >knows what it's doing (probably a driver mapping memory straight from an
% >ISA card). Or am I missing something?
%
% The test is the other way around from what you expect. Normally
% vremap will return NULL for adresses below the top of memory (since it
% probably would be a mistake to allow physical RAM to be mapped by a
% driver), my patch excludes the memory hole from that test.
%
% if (MAP_NR(offset) < MAP_NR(high_memory)
% && (offset < memory_hole_start || offset+size > memory_hole_end))
% return NULL;

OK, I was reading the test backwards. Makes sense now.

% >Doesn't look worth saving, as Stephen Early's patch looks more flexible
% >(not to mention supporting far more machines).
%
% Well my patch was a hack to get things working, with minimal changes
% to the memory management code in the kernel. It could most probably
% be done in a better way.

Stephen's patch supports arbitrary sets of memory ranges, and works with
any ACPI-compliant motherboard (in theory). It seems reasonable to my
eyes.

But there are two things from your patch that may be worth saving:

a) The fixes in vremap need to be put into ioremap. (Mostly a concept
transfer. No code can be saved.)

b) The detection code for the Triton I82437 chipset may be worth
transferring, assuming that it doesn't support ACPI.


Mark


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