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Re: kern/55958: pciback.hide parsing error
The following reply was made to PR kern/55958; it has been noted by GNATS.
From: Aleksey Arens <aza.sea.agenda%gmail.com@localhost>
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/55958: pciback.hide parsing error
Date: Wed, 27 Jan 2021 00:54:14 -0800
> Yes. But the Xen kernel probably needs to copy it at some point (even if
> it doens't know what it's copying). I'm not sure if it can copy somethin=
> arbitrary long (it may be limited e.g. to a page size).
As I understand it, Xen reads the cmdline string from an offset in the
module image passed-in to it. Cf.
> But there's something strange here: Xen is supposed to use multiboot, no=
> the NetBSD native boot protocol. In multiboot, the structures from
> bootinfo.h are not supposed to be used.
Correct. However, those arguments are not the ones being passed to
Xen, but to the module image that is being loaded by Xen.
> So I guess that the problem is more that /boot abuses bi_modulelist_entr=
> for internal structures in the multiboot case. The problem can probably
> be fixed in /boot without changing bootinfo.h at all.
In principle, yes. However, in that case, a different Xen-specific
format will need to be defined. Maybe a copy of bi_modulelist_entry
should be made, mentioning xen in its name? This is a piece of
bootinfo that is Xen-specific, and currently, it appears that the same
structure has merely been reused to cover both cases.
At any rate, an ability to use longer =E2=80=94 and ideally variable-lengt=
strings for /netbsd's boot arguments won't hurt in the long run,
though *that* specific topic (i.e. re: /netbsd's arguments) could
become a matter for another ticket. Right now, setting up a special
case for Xen (with fixed buffer length of e.g. 512, being a half of
Xen's limit of 1024 for the whole command line) might as well be more
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