On 11/3/2015 9:55 AM, Will Deacon wrote: > On Tue, Nov 03, 2015 at 09:44:52AM -0800, Mario Smarduch wrote: >> On 11/3/2015 8:33 AM, Christopher Covington wrote: >>> On 11/02/2015 06:51 PM, Mario Smarduch wrote: >>>> this is a re-post from couple weeks ago, please take time to review this >>>> simple patch which simplifies DEBUG_LL and prevents kernel crash on virtual >>>> platforms. >>>> >>>> Before this patch DEBUG_LL for 'dummy virtual machine': >>>> >>>> ( ) Kernel low-level debugging via EmbeddedICE DCC channel >>>> ( ) Kernel low-level debug output via semihosting I/O >>>> ( ) Kernel low-level debugging via 8250 UART >>>> ( ) Kernel low-level debugging via ARM Ltd PL01x Primecell >>>> >>>> In summary if debug uart is not emulated kernel crashes. >>>> And once you pass that hurdle, uart physical/virtual addresses are unknown. >>>> DEBUG_LL comes in handy on many occasions and should be somewhat >>>> intuitive to use like it is for physical platforms. For virtual platforms >>>> user may start daubting the host and get into a bigger mess. >>>> >>>> After this patch is applied user gets: >>>> >>>> (X) Kernel low-level debugging on QEMU Virtual Platform >>>> ( ) Kernel low-level debugging on Kvmtool Virtual Platform >>>> ..... above repeated .... >>>> >>>> The virtual addresses selected follow arm reference models, high in vmalloc >>>> section with high mem enabled and guest running with >= 1GB of memory. The >>>> offset is leftover from arm reference models. >>> >>> Which model? It doesn't appear to match the vexpress AEM/RTSM/FVP/whatever >>> which used 0x1c090000 for UART0. >> >> I recall QEMU virt model had it's own physical address map, for sure I saw the >> virtio-mmio regions assigned in some ARM document. Peter would you know? >> >> As far as kvmtool I'm not sure, currently PC1 COM1 port is used? Andre will that >> stay fixed? > > We make absolutely no guarantees about the memory map provided by kvmtool. > > Will > If that's also the case for qemu, then I guess the best you can do is find a way to dump the device tree. Find the uart, physical address and try figure out the virtual address. Pretty involved, hoped for something more automated since that's a handy feature. Thanks, - Mario. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
