[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Re: [PATCH] SeaBIOS/Xen: Compute the low RAM memory size in the BDA according to the e820
On 14/11/2011 03:36, "Kevin O'Connor" <kevin@xxxxxxxxxxxx> wrote: >> Like I said, I'm not an ACPI expert. But let say we decide to move >> this ACPI info structure to some other area, where there's less risk >> for it to be overwritten, like somewhere above 0xFC000000, wouldn't >> that prevent some Operating System with limited memory capabilities to >> access it ? > > If the OS can handle AML it can handle 32bit addresses. > >> Besides, it seems that SeaBIOS manages itself the space between >> 0xFC000000 and 4G, so it seems difficult to imagine to have a reserved >> space with a fixed address in there. > > On Xen, the PCI init code isn't used, so assuming this struct doesn't > need to live in real "ram", I think it could live just about anywhere > past the end of ram. Even with pciinit.c, addresses over 0xfc00000 > (with the exception of a few bytes for hpet, apic, ioapic, and bios > image) could be used. I suggest we stick it at FC000000, and shift hvmloader's mem_alloc() starting address up by one page to FC001000. The acpi build code will have to manually mem_hole_populate_ram() that one page before writing to it. This can then be documented in hvmloader/config.h which contains a description of, and defines for, the system memory map. This is by far the easiest solution to this problem; manually crafting an SSDT is a right pain in the arse, whereas this is maybe a 5-line patch. -- Keir > -Kevin > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxxxxxxxx > http://lists.xensource.com/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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