[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] x86: E801 memory "map" use implies no ACPI


  • To: Jan Beulich <jbeulich@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Mon, 23 Nov 2020 12:37:43 +0000
  • Authentication-results: esa1.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none
  • Cc: Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Mon, 23 Nov 2020 12:37:57 +0000
  • Ironport-sdr: LfTT8jqM+ceZyq4OIVrVm7MuMP5CMQWAov+SIlguifH+On8vrjS0240yx4yyRpUYxY/p7Qj5sK nr0UF9zlIu+Xeub1HXHEjP5wuE5wCvMQOgC62MxNcCshNP0oyXqbaP4uS8gNnyck/NmQkm47co AoMeTtyQNBHr5Nh+wihWIOldLFgkvNGz/fGaAVqAmQ7u+JhpEgDBLLjtv/+A2l45OCkHVpebVS vzOST8IM+W2pny7EKeGiqoBf6d+PJ83RaRHSwIryVA+qlVHAodE8fwMjnCGS6YSbIbTBa2eP+0 RXU=
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 20/11/2020 12:45, Jan Beulich wrote:
> ACPI mandates use of E820 (or newer, e.g. EFI), and in fact firmware
> has been observed to include E820_ACPI ranges in what E801 reports as
> available (really "configured") memory.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> TBD: Alternatively we could drop all use of E801 (and older), since
>      there shouldn't be any 64-bit systems not supporting the more
>      modern E820.

I'd definitely be in favour of deleting the legacy logic.  The very fact
that firmware has been observed to include E820_ACPI in E801 maps shows
that the change here isn't correct in practice.

I think we should go further and depend on the bootloader providing the
memory/video/etc details, which also rips out a lot of 16bit handling
code in the trampoline.

Judging by the context below, I think we should also drop various ACPI
related options.  Given its ubiquity these days, turning various bits of
ACPI off is only going to make problems worse.

~Andrew



 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.