[LinuxBIOS] LinuxBIOS panic room

pyro pyro at linuxlabs.com
Wed Sep 5 03:41:09 CEST 2007


On Wed, 5 Sep 2007, Carl-Daniel Hailfinger wrote:

> On 05.09.2007 01:40, Stefan Reinauer wrote:
> > * Peter Stuge <peter at stuge.se> [070905 01:29]:
> >> How usable is the CAR? I guess either the download will in fact write
> >> to flash immediately (bad idea!) or only initram would be downloaded
> >> first, and then the full lar.
> >
> > Why would that be a bad idea? I think writing the flash directly (except
> > bootblock) is an excellent idea, since this is the code that is executed
> > when
> >
> > a) the flash file is corrupt
> > b) a new lar is sent
> I still would like to try to enable RAM first. That will allow us to
> verify an image after flashing instead of having to redownload it over
> serial. Besides that, if there is some timing critical component in the
> flashing process, we don't want to wait for serial input.

Why not just load and run whatever is downloaded? If the flash is corrupt,
send a flash program followed by the image. If under development, perhaps
a ram init test or just something to dump registers. During production, it
might be memtest or other diagnostic. The one behavior that seems to
support every option (and options I haven't considered) is load and run.

That also lets you send raminit code, then a flash image and a flash
program that does the verify.

The less it actually does before handing control to the serial line, the
less likely it is to do the wrong thing.

I envision something like the Dragonball's bootstrap mode but not with
"b-records". A b-record is just a string of hex containing an absolute
address, a count and count bytes of data. When it gets a brec with a count
of 0, it jumps to the address.


> Carl-Daniel
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