From mboxrd@z Thu Jan  1 00:00:00 1970
Authentication-Results: mx.groups.io;
 dkim=missing; spf=pass (domain: redhat.com, ip: 209.132.183.28, mailfrom: lersek@redhat.com)
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28])
 by groups.io with SMTP; Mon, 15 Apr 2019 06:21:45 -0700
Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16])
	(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
	(No client certificate requested)
	by mx1.redhat.com (Postfix) with ESMTPS id 4042930ADBB6;
	Mon, 15 Apr 2019 13:21:37 +0000 (UTC)
Received: from lacos-laptop-7.usersys.redhat.com (ovpn-121-136.rdu2.redhat.com [10.10.121.136])
	by smtp.corp.redhat.com (Postfix) with ESMTP id 254145C1B4;
	Mon, 15 Apr 2019 13:21:33 +0000 (UTC)
Subject: Re: [edk2-devel] [PATCH v2 23/31] OvmfPkg/XenPlatformPei: Reserve VGA memory region, to boot Linux
To: devel@edk2.groups.io, anthony.perard@citrix.com
Cc: Jordan Justen <jordan.l.justen@intel.com>,
 Ard Biesheuvel <ard.biesheuvel@linaro.org>,
 Julien Grall <julien.grall@arm.com>, xen-devel@lists.xenproject.org
References: <20190409110844.14746-1-anthony.perard@citrix.com>
 <20190409110844.14746-24-anthony.perard@citrix.com>
From: "Laszlo Ersek" <lersek@redhat.com>
Message-ID: <a0742ad3-7540-95ca-ce25-cb02af48e2de@redhat.com>
Date: Mon, 15 Apr 2019 15:21:33 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <20190409110844.14746-24-anthony.perard@citrix.com>
X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Mon, 15 Apr 2019 13:21:42 +0000 (UTC)
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit

On 04/09/19 13:08, Anthony PERARD wrote:
> Linux panic if this region isn't reserved.

Please expand "this" (just copy from the subject).

with that,

Acked-by: Laszlo Ersek <lersek@redhat.com>

Thanks
Laszlo

> 
> When Linux is booted on EFI system, it expects the memory at 0xa0000 to
> _not_ be conventional memory. Otherwise a variable isn't initialised
> properly and Linux panic when a virtual console/terminal is asked to be
> created.
> 
> See for more detail:
> https://lists.xenproject.org/archives/html/xen-devel/2019-03/msg02139.html
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
>  OvmfPkg/XenPlatformPei/Xen.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
> index 7b503f2c4e..25f12c2f9c 100644
> --- a/OvmfPkg/XenPlatformPei/Xen.c
> +++ b/OvmfPkg/XenPlatformPei/Xen.c
> @@ -294,6 +294,12 @@ XenPublishRamRegions (
>    Status = XenGetE820Map (&E820Map, &E820EntriesCount);
>    ASSERT_EFI_ERROR (Status);
>  
> +  AddMemoryBaseSizeHob (0, 0xA0000);
> +  //
> +  // Video memory + Legacy BIOS region, to allow Linux to boot.
> +  //
> +  AddReservedMemoryBaseSizeHob (0xA0000, BASE_1MB - 0xA0000, TRUE);
> +
>    for (Index = 0; Index < E820EntriesCount; Index++) {
>      UINT64 Base;
>      UINT64 End;
> @@ -307,6 +313,16 @@ XenPublishRamRegions (
>      Base = ALIGN_VALUE (Entry->BaseAddr, (UINT64)EFI_PAGE_SIZE);
>      End = (Entry->BaseAddr + Entry->Length) & ~(UINT64)EFI_PAGE_MASK;
>  
> +    //
> +    // Ignore the first 1MB, this is handled before the loop.
> +    //
> +    if (Base < BASE_1MB) {
> +      Base = BASE_1MB;
> +    }
> +    if (Base >= End) {
> +      continue;
> +    }
> +
>      switch (Entry->Type) {
>      case EfiAcpiAddressRangeMemory:
>        AddMemoryRangeHob (Base, End);
>