On 09.10.2011, at 14:51, Peter Maydell wrote: > On 9 October 2011 13:06, Francis Moreau <francis.m...@gmail.com> wrote: >> On Sun, Oct 9, 2011 at 12:48 PM, Peter Maydell <peter.mayd...@linaro.org> >> wrote: >>> On 9 October 2011 09:28, Francis Moreau <francis.m...@gmail.com> wrote: >>>> I'm trying to use qemu to emulate the ARM realview-pb-a8 and more >>>> specifically I'd like to boot using the SD interface. >>>> >>>> However it looks like some devices are not emulated at all on this >>>> platform. >>> >>> Correct; not all devices are emulated. > >> May I suggest to report that a platform is partially supported when >> doing "qemu -M ?" > > I suspect that (in the sense you seem to be using "partially supported") > would cover almost all the platforms QEMU supports. Device and board > modelling is not trivial, and the typical state is that devices may be > missing, or have unimplemented features, or have bugs. > > The platform is supported in the sense that if you report regressions > (ie things that used to work and have broken) I will look at them, and > if you submit patches to improve it I will review them. > >> However, those are still missing: >> >> amba_device_register failed to register dev:smc >> amba_device_register failed to register dev:sctl >> amba_device_register failed to register dev:wdog >> amba_device_register failed to register dev:sci0 >> amba_device_register failed to register dev:ssp0 >> amba_device_register failed to register fpga:aaci > > Do you actually *need* these devices? If so, you're > going to need to model them. (except "fpga:aaci", which > is the PL041 audio; there are patches going through review > for that currently.) But in general Linux will quite happily > boot even if some of the minor devices are missing. > >> In your opinion, which plateform should I use to get a fully supported >> platform based on ARMv7 cpu ? > > I would recommend vexpress-a9 over realview-pb-a8 simply because > it's newer; nobody cares much about pb-a8 hardware any more. > The actual level of support (in terms of which devices are > present and how fully featured they are) is about the same, though. > >>> NB: when booting off SD card make sure you use >>> "-drive if=sd,cache=writeback,file=your-sd.img", otherwise you >>> will get the writethrough cache and really poor I/O performance. >>> [the slight catch is that if your *host* system crashes you >>> may get disk corruption, but typically for ARM emulation use >>> cases that is acceptable.] >> >> Thanks for the tip but why not making writeback the defaut ? > > Because of the 'slight catch' I mentioned.
cache=writeback survives host crashes. The only reason writethrough is the default is Windows XP which doesn't issue flushes properly, so there cache=writeback can lead to data loss. Linux guests are fine. Alex
