Re: [Xen-devel] [REBASE] xen: patches (against Linux kernel) for supporting efi

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.05.13 at 13:05, Eric Shelton <eshelton@xxxxxxxxx> wrote:
> This does not appear to be entirely correct, although it appears you
> are describing the intended design.  For one, if you look at
> efi_config_init() in efi.c, a hypercall is used to obtain the address
> of the config table.  However, the table entries have different sizes
> (see efi_config_table_64_t and efi_config_table_32_t).  This affects
> (1) how much memory is mapped for the config table, and (2) accessing
> the table entries at the correct addresses.  Thus, dom0 has to know
> whether EFI is 32 or 64 bit for at least this aspect, at least under
> how XEN_FW_EFI_CONFIG_TABLE is presently implemented.  However, as
> currently implemented, it appears there is a "bogus" hypervisor
> interface that overlooks this "obvious" issue.  This might be
> corrected by having the hypervisor mediate access to the config table
> rather than depending on dom0 to directly map and access the config
> table.

Dealing with this in the hypervisor is pointless - we don't want to
make a 32-bit clone of the table (the more that there's no
guarantee we wouldn't truncate addresses). Instead, the Dom0
code simply should use efi_config_table_64_t instead of
efi_config_table_t.

Jan


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