sd card support

[Wim Vervoorn]

Hello Kevin,

I am trying to use the sdcard support in SeaBIOS.

It is working but the performance is far from optimal. As far as I was able to see this is because the current support is polling only.

Do you know if there are plans to make dma versions of the code available?

Best regards,

Wim Vervoorn

[Kevin O'Connor]

On Tue, Jan 26, 2016 at 04:17:54PM +0000, Wim Vervoorn wrote:
> Hello Kevin,
>
> I am trying to use the sdcard support in SeaBIOS.
>
> It is working but the performance is far from optimal. As far as I
> was able to see this is because the current support is polling only.
>
> Do you know if there are plans to make dma versions of the code available?

I'm not aware of any plan.

Normally SeaBIOS disk drivers are only used to load the boot loader
and kernel, which is usually under 10 megs of data.  How much data are
you loading and how much time is it taking?

The SeaBIOS code doesn't enable the faster SD card speeds nor enable
the additional data lines.  If additional performance is needed I
suspect it would be sufficient to update the init sequence to do that.

-Kevin

[Wim Vervoorn]

Hello Kevin,

The data required varies. You are right that it is not huge but it impacts the boot time quite a bit.

It is good to know there aren't any plans until now. It would be a pitty to start a development while this is already underway.

Best Regards,

Wim Vervoorn

Eltan B.V.
Ambachtstraat 23
5481 SM Schijndel
The Netherlands

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-----Original Message-----
From: Kevin O'Connor [mailto:[e-mail]] 
Sent: Tuesday, January 26, 2016 6:02 PM
To: Wim Vervoorn 
Cc: [e-mail]
Subject: Re: [SeaBIOS] sd card support

On Tue, Jan 26, 2016 at 04:17:54PM +0000, Wim Vervoorn wrote:
> Hello Kevin,
>
> I am trying to use the sdcard support in SeaBIOS.
>
> It is working but the performance is far from optimal. As far as I was 
> able to see this is because the current support is polling only.
>
> Do you know if there are plans to make dma versions of the code available?

I'm not aware of any plan.

Normally SeaBIOS disk drivers are only used to load the boot loader and kernel, which is usually under 10 megs of data.  How much data are you loading and how much time is it taking?

The SeaBIOS code doesn't enable the faster SD card speeds nor enable the additional data lines.  If additional performance is needed I suspect it would be sufficient to update the init sequence to do that.

-Kevin