Re: [Xen-devel] [PATCH v1 3/3] efi: Implement 'efi=attr' Xen command line to map Runtime services with no attributes.

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> 04/24/15 10:48 PM >>>
>For example on Dell machines we see:
>
>(XEN)  00000fed18000-00000fed19fff type=11 attr=8000000000000000
>(XEN) Unknown cachability for MFNs 0xfed18-0xfed19
>
>Lets allow them to be mapped as WB.

UC ...

>+> `attr`
>+
>+> Default: `false`
>+
>+>> Allows mapping of RuntimeServices which have no cachability attribute
>+>> set as UC.
 
 ... as you correctly say here. But if you want to not allow specifying the 
caching
mode (which is fine by me) the option name ought to contain "uc" in some way,
e.g. "attr-uc".

>--- a/xen/common/efi/boot.c
>+++ b/xen/common/efi/boot.c
>@@ -1105,7 +1105,33 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE 
>*SystemTable)
 >#ifndef CONFIG_ARM /* TODO - runtime service support */
 >
 >static bool_t __initdata efi_rs_enable = 1;
>-boolean_param("efi-rs", efi_rs_enable);
>+static bool_t __initdata efi_attr;

And the variable name also ought to reflect the intended caching mode, or at 
least the fact
this this is an override.

>@@ -1209,9 +1235,10 @@ void __init efi_init_memory(void)
             >prot |= _PAGE_PWT | _PAGE_PCD | MAP_SMALL_PAGES;
         >else
         >{
>-            printk(XENLOG_ERR "Unknown cachability for MFNs %#lx-%#lx\n",
>-                   smfn, emfn - 1);
>-            continue;
>+            printk(XENLOG_ERR "Unknown cachability for MFNs %#lx-%#lx %s\n",
>+                   smfn, emfn - 1, efi_attr ? "assuming WB" : "");
>+            if ( !efi_attr )
>+                continue;
         
UC again (together with properly updating prot).

Jan


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