Re: [PATCH] hw/i386/pc: Document pc_system_ovmf_table_find

From: Tom Lendacky <thomas.lendacky@amd.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>,
	"Dov Murik" <dovmurik@linux.ibm.com>,
	qemu-devel@nongnu.org
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	James Bottomley <jejb@linux.ibm.com>
Subject: Re: [PATCH] hw/i386/pc: Document pc_system_ovmf_table_find
Date: Tue, 29 Jun 2021 08:28:12 -0500	[thread overview]
Message-ID: <faf8b5b6-435d-44fb-a198-0c5382dd12b4@amd.com> (raw)
In-Reply-To: <0fcb8bf0-f149-e0e6-5dde-8c21df96887c@redhat.com>

On 6/29/21 2:11 AM, Philippe Mathieu-Daudé wrote:
> On 6/29/21 7:56 AM, Dov Murik wrote:
>> On 29/06/2021 1:03, Tom Lendacky wrote:
>>> On 6/22/21 7:58 AM, Dov Murik wrote:
>>

>> (a) add a 'static bool ovmf_table_parsed' which will be set to true at
>> the beginning of pc_system_parse_ovmf_flash(). Then, at the beginning of
>> pc_system_ovmf_table_find add: assert(ovmf_table_parsed).
>>
>> (b) (ab)use our existing ovmf_table_len static variable: initialize it
>> to -1 (meaning that we haven't parsed the OVMF flash yet). When looking
>> for the table set it to 0 (meaning that OVMF table doesn't exist or is
>> invalid). When a proper table is found and copied to ovmf_table, then
>> set it to the real length (>= 0). At the beginning of
>> pc_system_ovmf_table_find add: assert(ovmf_table_len != -1). (this -1
>> can be #define OVMF_FLASH_NOT_PARSED -1).
>>
>>
>> Phil, Tom, James: which do you prefer? other options? Rust enum? ;-)
> 
> Since we are discussing code that should not be called, I don't have
> strong preference as long as we keep the code easy to review :)
> 
> With that in mind, (a) seems simpler.

Yes, to me (a) seems simpler, too.

Thanks,
Tom

> 
> Regards,
> 
> Phil.
> 