Hi all,
Most of 32-bit kernels (Unix/OS/whatever) usually have PAE support, so in fact they can cope with 36 bits of memory. The CPU PAE support started around Pentium. Windows XP+ has support for this.
I think one can go with 2GB MMIO hole. The PCIe > 4GB is a question, I don't think Windows have good support for this. So, using 2GB memory hole and having MMIO < 4GB seems like a good idea.
Thanks Rudolf
Hi,
I think one can go with 2GB MMIO hole.
Agreeing here. We have PAE. Non-ancient 32bit kernels should support and use it, for both security reasons (nox support requires PAE page table format) and accessing physical address space above 4G.
The PCIe > 4GB is a question, I don't think Windows have good support for this.
Depends on the version. Recent windows versions have no problems handling it. WinXP throws a BSOD though in case it finds a 64bit mmio window described in _SB.PCI0._CRS ...
cheers, Gerd
I'm getting the sense here that reasonably modern CPUs can easily handle the 2G hole. From what I've seen, it would not cause trouble for older CPUs because they're most likely to be in small systems that are not likely to have more than 2G memory anyway (I'm thinking of the vortex).
The 2G hole seems like a reasonable way go to.
ron
On Mon, Jun 6, 2016 at 1:01 AM Gerd Hoffmann kraxel@redhat.com wrote:
Hi,
I think one can go with 2GB MMIO hole.
Agreeing here. We have PAE. Non-ancient 32bit kernels should support and use it, for both security reasons (nox support requires PAE page table format) and accessing physical address space above 4G.
The PCIe > 4GB is a question, I don't think Windows have good support for this.
Depends on the version. Recent windows versions have no problems handling it. WinXP throws a BSOD though in case it finds a 64bit mmio window described in _SB.PCI0._CRS ...
cheers, Gerd
-- coreboot mailing list: coreboot@coreboot.org https://www.coreboot.org/mailman/listinfo/coreboot
-
Gerd Hoffmann -
ron minnich -
Rudolf Marek