Hi all, I've updated OVMF to use the SATA controller, so that I could finally use the Q35 machine specification with OVMF.
However, upon doing so I found that the (SATA) CD-ROM wouldn't work anymore; directories on the CD-ROM can be read, but the file listing contained only garbage. After some _very_ tedious debugging I've found this to be an issue with the ahci driver in qemu; ATAPI PIO transfers seem to be slightly buggy. Enabling 'atapi_dma' transfers in atapi driver (even for PIO mode) makes everything work again. I still fail to see _why_ this is be the case; the logfiles in both cases are pretty identical. Originally I thought that somehow the big qemu lock plays a role here, but OVMF accesses the ahci HBA only ever _after_ all transfers are complete. And again, access patterns are identical in both cases. So if anyone has another idea here ... Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage h...@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
