linux-kernel - Re: [PATCH v4 6/7] firmware/efi: Process CXL Component Events

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Date: Mon, 18 Dec 2023 10:13:16 -0800
From: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
To: Ira Weiny <ira.weiny@...el.com>, Dan Williams <dan.j.williams@...el.com>,
 Jonathan Cameron <jonathan.cameron@...wei.com>,
 Shiju Jose <shiju.jose@...wei.com>
Cc: Yazen Ghannam <yazen.ghannam@....com>, Davidlohr Bueso
 <dave@...olabs.net>, Dave Jiang <dave.jiang@...el.com>,
 Alison Schofield <alison.schofield@...el.com>,
 Vishal Verma <vishal.l.verma@...el.com>, Ard Biesheuvel <ardb@...nel.org>,
 linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-cxl@...r.kernel.org
Subject: Re: [PATCH v4 6/7] firmware/efi: Process CXL Component Events

On 12/15/2023 3:26 PM, Ira Weiny wrote:
> BIOS can configure memory devices as firmware first.  This will send CXL
> events to the firmware instead of the OS.  The firmware can then send
> these events to the OS via UEFI.
> 
> UEFI v2.10 section N.2.14 defines a Common Platform Error Record (CPER)
> format for CXL Component Events.  The format is mostly the same as the
> CXL Common Event Record Format.  The difference is the use of a GUID in
> the Section Type rather than a UUID as part of the event itself.
> 
> Add EFI support to detect CXL CPER records and call a registered
> notifier with the event.  Enforce that only one notifier call can be
> registered at any time.
> 
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> 

[snip]

> +	struct {
> +		u32 length;
> +		u64 validation_bits;
> +		struct cper_cxl_event_devid {
> +			u16 vendor_id;
> +			u16 device_id;
> +			u8 func_num;
> +			u8 device_num;
> +			u8 bus_num;
> +			u16 segment_num;
> +			u16 slot_num; /* bits 2:0 reserved */
> +			u8 reserved;
> +		} device_id __packed;
> +		struct cper_cxl_event_sn {
> +			u32 lower_dw;
> +			u32 upper_dw;
> +		} dev_serial_num __packed;
> +	} hdr __packed;
> +
> +	union cxl_event event;
> +} __packed;
> +

For some reason, prefixing the struct name with __packed attribute seems 
to do the job. ("__packed device_id" and "__packed dev_serial_num").

Thanks,
Smita