Re: [Xen-devel] Re: [PATCH] SeaBIOS/Xen: Compute the low RAM memory size in the BDA according to the e820

[Keir Fraser <keir.xen@gmail.com>]

On 14/11/2011 19:25, "Julian Pidancet" <julian.pidancet@gmail.com> wrote:

> On Mon, Nov 14, 2011 at 1:23 PM, Keir Fraser <keir@xen.org> wrote:
>> On 14/11/2011 08:53, "Keir Fraser" <keir.xen@gmail.com> wrote:
>> 
>>> On 14/11/2011 03:36, "Kevin O'Connor" <kevin@koconnor.net> wrote:
>>> 
>>>> 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.
>> 
>> Like the attached patch (untested), which is a bit larger than anticipated,
>> but actually allows code to be net deleted. :-)
>> 
> 
> I just tested your patch with Windows 7 and Linux guest booted from iPXE.
> 
> Everything seems to work fine. SeaBIOS reports the following e820:
> 
> (XEN) HVM23: e820 map has 6 items:
> (XEN) HVM23:   0: 0000000000000000 - 000000000009f400 = 1 RAM
> (XEN) HVM23:   1: 000000000009f400 - 00000000000a0000 = 2 RESERVED
> (XEN) HVM23:   2: 00000000000f0000 - 0000000000100000 = 2 RESERVED
> (XEN) HVM23:   3: 0000000000100000 - 000000003f7ff000 = 1 RAM
> (XEN) HVM23:   4: 000000003f7ff000 - 000000003f800000 = 2 RESERVED
> (XEN) HVM23:   5: 00000000fc000000 - 0000000100000000 = 2 RESERVED
> 
> The ACPI code in Linux reports the right PCI memory window:
> 
> [    0.338966] PCI: Using host bridge windows from ACPI; if necessary,
> use "pci=nocrs" and report a bug
> [    0.340000] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
> [    0.341029] pci_root PNP0A03:00: host bridge window [io  0x0000-0x0cf7]
> [    0.341965] pci_root PNP0A03:00: host bridge window [io  0x0d00-0xffff]
> [    0.342965] pci_root PNP0A03:00: host bridge window [mem
> 0x000a0000-0x000bffff]
> [    0.343965] pci_root PNP0A03:00: host bridge window [mem
> 0xf0000000-0xfbffffff]
> 
> Can you ship it ?

Done. Xen-unstable:24143

 Thanks,
 Keir