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

Re: [PATCH v5 1/4] xen/riscv: add VM space layout


  • To: Oleksii <oleksii.kurochko@xxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Mon, 24 Apr 2023 11:25:13 +0200
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=nC/EQbazuieMKA+YFrsvUJIrKhm83FWlyCJoYI8GTUs=; b=JeKM6dy6HnNMzwTXs3D+rsmgV9g/aZBx1FP5anqiZI7wEYRW4+3DxJV+j4AVv7EWxpuiQZIkPNYgVIfnwuQ0YrZ7OvYVf9xIQyejQdTjdi1kwX7BYhtiZpi7PDz9FhYljFUfwwgTXfMh342L6KVAj4RHOgdhH0Sbj7wUftf4kaXjXrVG8WvzHLBjeg7ZfapD90fJ9qiG9+hcKuIONxm8OL6wq/hNFWBpVaRfo53cFKNBy146LwfKjUHkcftnN0B28ATUMobpflIcZ+ed8Xg9jOg+Tw/ifvz+R7sqeHn6BRsM4PKrGIp5wuhc576QYCFzaeISQrqM+p9BnFc66fEtrw==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=habRExT0SSnUBjvg3WdJK0dZLI4P1d1UwfcixYJx+CYz3NH7fryfKU4eXrVgTUaIXtN+XH/R0ovJJ29ZHRRkGdoBTFzlX8ABucCRLakJrHpDWVhxPopdvdUmp+XpN9twyYIV6vV5upmSWgtfvvoiDJEpra6qlkwB2GzvHq8mywO960LYDvffqyXpkMOV4HUDDKc2XLiez4sL+2nXH0bPXAe/FlyVj0u35ycldHHYpL1CSNrBOuDUSjtkrdml67BMeIY6KpqLw31eqpw1bbQuXKMP/x9djjbkh8UlAfGA9jBuoZEIvAjfMk9jhMV6LtmcuCtH/x+PMk65Zma1Dsejrw==
  • Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=suse.com;
  • Cc: Julien Grall <julien@xxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Gianluca Guida <gianluca@xxxxxxxxxxxx>, Bob Eshleman <bobbyeshleman@xxxxxxxxx>, Alistair Francis <alistair.francis@xxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 24 Apr 2023 09:25:39 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 21.04.2023 16:41, Oleksii wrote:
> On Thu, 2023-04-20 at 14:58 +0200, Jan Beulich wrote:
>> On 19.04.2023 17:42, Oleksii Kurochko wrote:
>>> + *
>>> ===================================================================
>>> =========
>>> + *    Start addr    |   End addr        |  Size  | VM area
>>> description
>>> + *
>>> ===================================================================
>>> =========
>>> + * FFFFFFFFC0000000 |  FFFFFFFFC0200000 |  2 MB  | Xen
>>> + * FFFFFFFFC0200000 |  FFFFFFFFC0600000 |  4 MB  | FDT
>>> + * FFFFFFFFC0600000 |  FFFFFFFFC0800000 |  2 MB  | Fixmap
>>
>> These are all L2 slot 511 aiui, which may be worth mentioning
>> especially since
>> the top bits don't match the top bits further down in the table
>> (because of the
>> aliasing).
> 
> Than I'll add one more column where I'll put slot number
> 
>>
>>> + *     .................. unused ..................
>>
>> This is covering slot 510, which again may be worth mentioning.
>>
>>> + * 0000003200000000 |  0000007f40000000 | 331 GB | Direct map(L2
>>> slot: 200-509)
>>> + * 0000003100000000 |  0000003140000000 |  1 GB  | Frametable(L2
>>> slot: 196-197)
>>
>> 1Gb is, if I'm not mistaken, a single L2 slot.
> Yeah, it can be misunderstood. I meant [196, 197), so 197 isn't
> included. I'll update the table.
> 
>>
>> Also assuming a 32-byte struct page_info (I don't think you'll get
>> away with
>> less than that, when even Arm32 requires this much), there's a
>> mismatch
>> between direct map and frame table size: With 4k pages, the scaling
>> factor
>> would be 128 if I'm not mistaken. So perhaps you really mean 3Gb here
>> to
>> cover for (slightly more than) the 331Gb of memory you mean to be
>> able to
>> map?
> For RV64 page_info size will be 56-byte and 32-byte for RV32 but you
> are right it should 3 Gb in that case what will be enough ( taking into
> account both available sizes of page_info structure ).

Since you say "both": I don't expect you will want to use 3Gb for RV32
there? The table is, at least for now, for RV64 / Sv39 only anyway.

Jan



 


Rackspace

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