>From: Jeremy Fitzhardinge [mailto:jeremy@xxxxxxxx] >Sent: Tuesday, March 24, 2009 1:43 PM > >Tian, Kevin wrote: >> The reason why those useless code are prevented, is in case of >> clobberring 0-1M area which if contains valid Xen content. in >> acpi_save_state_mem, dom0's wakeup code is copied to area >> allocated in acpi_reserve_bootmem. If every Xen's usage on 0-1M >> is based on copy-on-use style, such as trampoline code for AP >> boot, it's ok. But I'm not sure whether Xen puts some persistent >> content there. IIRC, that boot time allocation usually returns sth >> like 0x90000 since wakeup stub is first run in real mode. But if >> for dom0 alloc_bootmem_low never gives <1M page, then this >> prevention could be skipped as your thought. >> > >Yes, but the memory allocated is only in 0-1M in dom0's >pseudo-physical >space, not in Xen's machine space. It allocates the memory and does a >virt_to_phys on it, but there's no special effort to remap it >as mfns or >anything. There should be no possible conflict with Xen's use of the >real 0-1M region. OK, then it's safe to avoid that change. I had thought that dom0's 0-1M is identity-mapped to machine 0-1M... :-) Thanks, Kevin > >Not that I've actually tried to execute that patch yet, so I >could well >be overlooking something... > > J > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
