Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1465930
| From | One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC |
| Date | 2016-08-19 04:40 +0200 |
| Message-ID | <s7HSW-892-37@gated-at.bofh.it> (permalink) |
| References | <s7fMZ-62b-3@gated-at.bofh.it> <s7sqR-6Jo-3@gated-at.bofh.it> <s7sAy-6Nh-29@gated-at.bofh.it> <s7twB-7tk-25@gated-at.bofh.it> |
| Organization | Intel Corporation |
On Thu, 18 Aug 2016 05:12:54 -0600 "Jan Beulich" <JBeulich@suse.com> wrote: > >>> On 18.08.16 at 12:16, <andrew.cooper3@citrix.com> wrote: > > On 18/08/16 11:06, Jan Beulich wrote: > >>>>> On 17.08.16 at 22:32, <konrad.wilk@oracle.com> wrote: > >>> Looking at the kernel it assumes that WB is ok for 640KB->1MB. > >>> The comment says: > >>> " /* Low ISA region is always mapped WB in page table. No need to track > > *" > >> As per above it's not clear to me what this comment is backed by. > > > > This states what is in the pagetables. Not the combined result with MTRRs. > > > > WB in the pagetables and WC/UB in the MTRRs is a legal combination which > > functions correctly. > > True, but then again - haven't I been told multiple times that Linux > nowadays prefers to run without using MTRRs? The BIOS sets up the fixed MTRR registers for the 640K-1MB window. Those are separate to the variable range MTRR registers used for main memory with specific mappings for segments A000 to BFFF then C000-C7FF / C800-CFFF / etc up to FFFF. Alan
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-08-17 22:40 +0200
Re: XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC "Jan Beulich" <JBeulich@suse.com> - 2016-08-18 12:10 +0200
Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC Andrew Cooper <andrew.cooper3@citrix.com> - 2016-08-18 12:20 +0200
Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC "Jan Beulich" <JBeulich@suse.com> - 2016-08-18 13:20 +0200
Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-08-19 04:40 +0200
Re: [Xen-devel] XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-08-19 17:30 +0200
Re: XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> - 2016-08-19 17:00 +0200
Re: XSA 154 and ISA region (640K -> 1MB) WB cache instead of UC "Jan Beulich" <JBeulich@suse.com> - 2016-08-19 17:20 +0200
csiph-web