On 15.09.2007 18:27, fedorawiki-noreply@fedoraproject.org wrote:
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The following page has been changed by PaulFrields: http://fedoraproject.org/wiki/Docs/Beats/Kernel?action=diff&rev2=112&... [...]
- The kernel-PAE, for use in 32-bit x86 systems with more
than 4GB of RAM, or with CPUs that have a NX (No eXecute) feature. This kernel support both uniprocessor and multi-processor systems. Configured sources are available in the `kernel-PAE-devel` package.
This reminded me of: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=...
Quoting Patch description:
i386: divorce CONFIG_X86_PAE from CONFIG_HIGHMEM64G
PAE is useful for more than supporting more than 4GB RAM. It supports expanded swapspace and NX executable protections. Some users may want NX or expanded swapspace support without the overhead or instability of highmem. For these reasons, the following patch divorces CONFIG_X86_PAE from CONFIG_HIGHMEM64G.
Which brings me to the point why I'm writing this mail: should we enable PAE by default after F8 is out and ship a HIGHMEM64G-Kernel instead on x86-32? Then normal users on x86-32 can benefit from NX by default. Or is that considered "not worth the trouble because we ship execshield already"?
Further: Does PAE-by-default still make lots of machines unbootable (I doubt that for newer machines, as some-well-known-other-os enables PAE since its service pack 2 by default iirc)? If we suspect it still does: could we fix that by some kind of automatic "if machine is newer than ${year}" check in the kernel?
Just wondering.
CU knurd
Thorsten Leemhuis wrote:
Which brings me to the point why I'm writing this mail: should we enable PAE by default after F8 is out and ship a HIGHMEM64G-Kernel instead on x86-32? Then normal users on x86-32 can benefit from NX by default. Or is that considered "not worth the trouble because we ship execshield already"?
Further: Does PAE-by-default still make lots of machines unbootable (I doubt that for newer machines, as some-well-known-other-os enables PAE since its service pack 2 by default iirc)? If we suspect it still does: could we fix that by some kind of automatic "if machine is newer than ${year}" check in the kernel?
Just wondering.
Yes, it does still tend to break machines, especially laptops and older machines (we run into this a lot with Xen, since we only ship a PAE variant there). Unfortunately, PAE is a compile time option, not something that can (currently) be turned on or off at runtime. It would be nice to make it a runtime option (IIRC, OpenSolaris does this), but I don't know if it is worth the effort given that 32-bit should be becoming less and less common.
Chris Lalancette
On 16.09.2007 20:14, Chris Lalancette wrote:
Thorsten Leemhuis wrote:
Which brings me to the point why I'm writing this mail: should we enable PAE by default after F8 is out and ship a HIGHMEM64G-Kernel instead on x86-32? Then normal users on x86-32 can benefit from NX by default. Or is that considered "not worth the trouble because we ship execshield already"?
Further: Does PAE-by-default still make lots of machines unbootable (I doubt that for newer machines, as some-well-known-other-os enables PAE since its service pack 2 by default iirc)? If we suspect it still does: could we fix that by some kind of automatic "if machine is newer than ${year}" check in the kernel?
Just wondering.
Yes, it does still tend to break machines,
:-/ -- as expected... Nevertheless thx for sharing your experiences.
[...] Unfortunately, PAE is a compile time option, not something that can (currently) be turned on or off at runtime. It would be nice to make it a runtime option (IIRC, OpenSolaris does this), but I don't know if it is worth the effort given that 32-bit should be becoming less and less common.
Agreed -- but on the other hand x86-32 still is quite famous even on x86-64 machines. Well, sooner or later that should change :-)
Cu knurd
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