* [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0
@ 2023-04-04 9:19 Jan Beulich
2023-04-04 10:04 ` Roger Pau Monné
2023-04-04 10:34 ` Andrew Cooper
0 siblings, 2 replies; 3+ messages in thread
From: Jan Beulich @ 2023-04-04 9:19 UTC (permalink / raw
To: xen-devel@lists.xenproject.org
Cc: Andrew Cooper, Wei Liu, Roger Pau Monné
Besides a printk() the main effect is slight corruption of the start
info magic: While that's meant to be xen-3.0-x86_64, it wrongly ended
up as xen-3.0-x86_64p.
Note that no known users exist that would have developed a dependency on
the bogus magic string. In particular Linux, NetBSD, and mini-os have
been checked.
Fixes: 460060f83d41 ("libelf: use for x86 dom0 builder")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
RFC: While Linux works fine with the adjustment, I'm not entirely
certain of external tools (crash?) having grown a dependency. It
may be worth noting that XenoLinux and its forward ports never had
this ELF note in 64-bit kernels, so in principle it may be
reasonable to expect that no such dependency exists anywhere.
Prior to "x86/PV32: restore PAE-extended-CR3 logic" that (meaningless
for 64-bit domains) VM-assist could also be engaged, based on the ELF
note's value. I expect that change to go in first, at which point the
description here is going to be correct (in not mentioning this VM-
assist aspect).
---
v2: Extend description.
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -459,8 +459,13 @@ int __init dom0_construct_pv(struct doma
compat = is_pv_32bit_domain(d);
if ( elf_64bit(&elf) && machine == EM_X86_64 )
+ {
compatible = true;
+ /* Zap meaningless setting which kernels may carry by mistake. */
+ parms.pae = 0;
+ }
+
if ( elf_msb(&elf) )
compatible = false;
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0
2023-04-04 9:19 [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0 Jan Beulich
@ 2023-04-04 10:04 ` Roger Pau Monné
2023-04-04 10:34 ` Andrew Cooper
1 sibling, 0 replies; 3+ messages in thread
From: Roger Pau Monné @ 2023-04-04 10:04 UTC (permalink / raw
To: Jan Beulich; +Cc: xen-devel@lists.xenproject.org, Andrew Cooper, Wei Liu
On Tue, Apr 04, 2023 at 11:19:08AM +0200, Jan Beulich wrote:
> Besides a printk() the main effect is slight corruption of the start
> info magic: While that's meant to be xen-3.0-x86_64, it wrongly ended
> up as xen-3.0-x86_64p.
>
> Note that no known users exist that would have developed a dependency on
> the bogus magic string. In particular Linux, NetBSD, and mini-os have
> been checked.
>
> Fixes: 460060f83d41 ("libelf: use for x86 dom0 builder")
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
> ---
> RFC: While Linux works fine with the adjustment, I'm not entirely
> certain of external tools (crash?) having grown a dependency. It
> may be worth noting that XenoLinux and its forward ports never had
> this ELF note in 64-bit kernels, so in principle it may be
> reasonable to expect that no such dependency exists anywhere.
>
> Prior to "x86/PV32: restore PAE-extended-CR3 logic" that (meaningless
> for 64-bit domains) VM-assist could also be engaged, based on the ELF
> note's value. I expect that change to go in first, at which point the
> description here is going to be correct (in not mentioning this VM-
> assist aspect).
Will look at it now.
Thanks, Roger.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0
2023-04-04 9:19 [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0 Jan Beulich
2023-04-04 10:04 ` Roger Pau Monné
@ 2023-04-04 10:34 ` Andrew Cooper
1 sibling, 0 replies; 3+ messages in thread
From: Andrew Cooper @ 2023-04-04 10:34 UTC (permalink / raw
To: Jan Beulich, xen-devel@lists.xenproject.org; +Cc: Wei Liu, Roger Pau Monné
On 04/04/2023 10:19 am, Jan Beulich wrote:
> Besides a printk() the main effect is slight corruption of the start
> info magic: While that's meant to be xen-3.0-x86_64, it wrongly ended
> up as xen-3.0-x86_64p.
>
> Note that no known users exist that would have developed a dependency on
> the bogus magic string. In particular Linux, NetBSD, and mini-os have
> been checked.
>
> Fixes: 460060f83d41 ("libelf: use for x86 dom0 builder")
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-04-04 10:35 UTC | newest]
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2023-04-04 9:19 [PATCH v2] x86/PV: ignore PAE_MODE ELF note for 64-bit Dom0 Jan Beulich
2023-04-04 10:04 ` Roger Pau Monné
2023-04-04 10:34 ` Andrew Cooper
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