On Mon, 20 Sep 2010, Paul E. McKenney wrote: > On Mon, Sep 20, 2010 at 06:37:05PM +0200, Arnd Bergmann wrote: > > On Monday 20 September 2010, Paul E. McKenney wrote: > > > o Kernel requirements > > > (https://wiki.linaro.org/Internal/TSC/MinutesToBeAgreed) > > > > > > > I still have two questions about stuff that came up here: > > > > * SD/MMC performance: Is this about device access, file systems or both? > > I think the file system level stuff is actually the more important > > part but I fear that what was discussed is the other one. > > The discussion didn't get into that level of detail. :-( > > > * highmem: Not sure what this was about. I guess we don't really want > > to enable this by default, but some people will want it anyway. > > Is this about run-time patching the code out of the kernel? > > I believe that this is related to LPAE -- the usual 32-bit-only DMA > devices in a >32-bit physical address space. But there was also > discussion about run-time patching for SMP alternatives, though I am > missing how this relates to highmem. Enlightenment?
I'm also interested in both of those topics as 1) I participated in the design of the SDIO stack (closely related to SD), and 2) I did the highmem implementation for ARM. Wrt SD/MMC performance, if we're talking about device access, then all the DMA-using hardware configs I've seen are only limited by the media speed which is typically much slower than a hard disk, or even a SSD for that matter (and so is the price). Wrt highmem: I can't see the link with highmem and SMP. As far as I know, highmem on ARM should be SMP safe already (the only SMP related issue I've seen has been fixed in commit 831e8047eb). Nicolas _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
