Jeremy Fitzhardinge wrote:
> Zachary Amsden wrote:
>> Doesn't this work and give a common entry point with the regular
>> kernel, eliminating all the need for string processing?
>
> Which string processing?
>
> J
>
The crazy string extraction Xen has to do to figure out hypervisor
features from the xen_guest section - which is a really bad idea.
Putting this in the kernel is unnecessary if you have a paravirt_ops
initialization function which can negotiate this information to the
hypervisor. Putting this code into Linux sets an extremely bad
precedent by encouraging ad-hoc, hypervisor specific sections to be put
in the kernel. It is ugly, gratuitous, and unnecessary change to
Linux, Please fix your loader so this doesn't need to be part of the
maintained Linux code:
/*
* __xen_guest information
*/
.macro utoa value
.if (\value) < 0 || (\value) >= 0x10
utoa (((\value)>>4)&0x0fffffff)
.endif
.if ((\value) & 0xf) < 10
.byte '0' + ((\value) & 0xf)
.else
.byte 'A' + ((\value) & 0xf) - 10
.endif
.endm
.section __xen_guest
.ascii "GUEST_OS=linux,GUEST_VER=2.6"
.ascii ",XEN_VER=xen-3.0"
.ascii ",VIRT_BASE=0x"
utoa __PAGE_OFFSET
.ascii ",HYPERCALL_PAGE=0x"
utoa ((__PHYSICAL_START+HYPERCALL_PAGE_OFFSET)>>PAGE_SHIFT)
.ascii ",FEATURES=writable_page_tables"
.ascii "|writable_descriptor_tables"
.ascii "|auto_translated_physmap"
.ascii "|pae_pgdir_above_4gb"
.ascii "|supervisor_mode_kernel"
#ifdef CONFIG_X86_PAE
.ascii ",PAE=yes"
#else
.ascii ",PAE=no"
#endif
.ascii ",LOADER=generic"
.byte 0
