Jan Beulich
2006-Jun-29 13:42 UTC
[Xen-devel] [PATCH] linux/x86: Initialize high_memory as early as possible
Also all other variables dependent on the same input(s). This is a prerequisite patch for two ones to follow. I will post a similar change for mainline Linux soon. Signed-off-by: jbeulich@novell.com _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2006-Jun-29 13:55 UTC
Re: [Xen-devel] [PATCH] linux/x86: Initialize high_memory as early as possible
On 29 Jun 2006, at 14:42, Jan Beulich wrote:> Also all other variables dependent on the same input(s). This is a > prerequisite patch for two ones to follow. I will > post a similar change for mainline Linux soon. > > Signed-off-by: jbeulich@novell.comIs this just for the usage in kunmap_atomic? Why did you change that, by the way: FIXADDR_START looked like a safe enough test to me. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jan Beulich
2006-Jun-29 14:03 UTC
Re: [Xen-devel] [PATCH] linux/x86: Initialize high_memory as early as possible
>>> Keir Fraser <Keir.Fraser@cl.cam.ac.uk> 29.06.06 15:55 >>> > >On 29 Jun 2006, at 14:42, Jan Beulich wrote: > >> Also all other variables dependent on the same input(s). This is a >> prerequisite patch for two ones to follow. I will >> post a similar change for mainline Linux soon. >> >> Signed-off-by: jbeulich@novell.com > >Is this just for the usage in kunmap_atomic? Why did you change that,Not only, also for the added check in xen_{create,destroy}_contiguous_region in another of the patches just sent.>by the way: FIXADDR_START looked like a safe enough test to me.This didn''t seem safe enough to me, and apparently also not to the original author (at least I attribute the FIXME comment to this) - after all not everything before FIXADDR_START is high memory. One could say that under DEBUG_HIGHMEM the check should be more strict (so that the subsequent BUG() condition fires in more broken cases), but without DEBUG_HIGHMEM it might be left as-is to avoid zapping incorrect page table entries. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Keir Fraser
2006-Jun-29 14:47 UTC
Re: [Xen-devel] [PATCH] linux/x86: Initialize high_memory as early as possible
On 29 Jun 2006, at 15:03, Jan Beulich wrote:> This didn''t seem safe enough to me, and apparently also not to the > original > author (at least I attribute the FIXME comment to this) - after all not > everything before FIXADDR_START is high memory. > One could say that under DEBUG_HIGHMEM the check should be more strict > (so that the subsequent BUG() condition fires in more broken cases), > but > without DEBUG_HIGHMEM it might be left as-is to avoid zapping incorrect > page table entries.Any kmap_atomic virtual address should be above FIXADDR_START. You have a point about debugging though (e.g., passing a non-atomic kmap address to kunmap_atomic). -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel