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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/video: Set EFI framebuffer to WC by default
On 06/11/2015 01:35 PM, Jan Beulich wrote: On 11.06.15 at 14:09, <ross.lagerwall@xxxxxxxxxx> wrote:Set the EFI framebuffer to write-combining by default. This makes booting somewhat faster, but more importantly avoids tripping the watchdog. In particular, before on my test machine, each frame redraw would take around 80ms, which can trip the 5s watchdog when constructing dom0, since it outputs something like 60 lines without processing pending softirqs.That would need fixing then. What are those 60 lines? I think it's the lines from "Testing NMI watchdog on all CPUs: ok" to "Scrubbing Free RAM". Both Linux and FreeBSD map the EFI framebuffer as write-combining by default, so I assume (hope) that this is a safe change to make.No, an unaware Dom0 OS may not work correctly when the frame buffer is WC. It also might come as a surprise to the Dom0 OS that there is a WC range in one of the MTRRs where none would be expected. Plus - why for EFI only? Because that's what other OSes did, but if it's not going to work... I can send a patch which we're currently using which sticks in a few process_pending_softirqs() in strategic places. -- Ross Lagerwall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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