Re: > 1GB on alpha. Patch to 1TB?
Guy Sotomayor (ggs@shiresoft.com)
Sat, 13 Mar 1999 11:18:42 -0800
Quoted mail:
> On Wed, Mar 10, 1999 at 11:57:38PM -0600, Bob McElrath wrote:
>> It seems simple to me to modify these two files to support up to 1TB memory
>> on the alpha, as opposed to the hard-coded limit of 1GB now. It appears the
>> 21172 will only decode 40 bits of address, not 64, but that's 1TB...
>
> With 32-bit PCI devices, it is difficult to get past 2GB RAM. More
> than that requires either bounce buffers or that PCI windows be
> adjusted at runtime to cope with the various outstanding DMA requests.
> Which would be cool, but i think fairly tricky to modify all the
> drivers to get right.
>
> However, there's no reason we can't support 2GB instead of 1.
---End quote
This is also a problem when you have multiple PCI busses. There is no
really good near term solution but 32bit PCI on large memory systems +
multiple PCI busses should probably be delt with together since they will
likely hit the same parts of the code.
TTFN - Guy
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