Date: Mon, 6 Apr 2009 13:42:21 -0400 From: John Baldwin <jhb@freebsd.org> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-hackers@freebsd.org, Sergey Babkin <babkin@verizon.net> Subject: Re: Patch for MS Hyper V (virtualization) Message-ID: <200904061342.22000.jhb@freebsd.org> In-Reply-To: <9bbcef730904061007y66a8440al3c43a6a6b6cd6ed6@mail.gmail.com> References: <1366225354.253456.1238948619308.JavaMail.root@vms124.mailsrvcs.net> <200904061154.19601.jhb@freebsd.org> <9bbcef730904061007y66a8440al3c43a6a6b6cd6ed6@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Monday 06 April 2009 1:07:38 pm Ivan Voras wrote: > 2009/4/6 John Baldwin <jhb@freebsd.org>: > > On Sunday 05 April 2009 12:23:39 pm Sergey Babkin wrote: >=20 > > Hmm, the problem is we need to be able to write to BARs to size them. = =C2=A0Any=20 OS > > needs to be able to do this to know what address space regions are being > > decoded by devices. =C2=A0We can't avoid writing to BARs. >=20 > I have only vague idea what BARs are and if it's the correct diagnosis > in this case, but the fact is that other operating systems (Windows, > Linux tested) work, so either there is a way around it or the original > premise is wrong-ish. Every OS writes to BARs to size them during boot. It's the defined procedu= re=20 for sizing them. A BAR is a base address register, and it is how a PCI=20 device gets memory and I/O port resources. OS (or BIOS) writes a starting= =20 address into the register to tell the PCI device where a given=20 resource "starts". =2D-=20 John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200904061342.22000.jhb>