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Handle single-byte reads from the bvmcons port (0x220) by returning

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0xff.  Some guests may attempt to read from this port to identify
psuedo-PNP ISA devices.  (The ie(4) driver in FreeBSD/i386 is one
example.)

Reviewed by:	grehan
This commit is contained in:
John Baldwin 2014-04-08 21:02:03 +00:00
parent 1f0283145c
commit 2cf4f7ef79
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=264277
1 changed files with 9 additions and 0 deletions
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9
usr.sbin/bhyve/consport.c
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@ -110,6 +110,15 @@ console_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
return (0);
}
/*
* Guests might probe this port to look for old ISA devices
* using single-byte reads. Return 0xff for those.
*/
if (bytes == 1 && in) {
*eax = 0xff;
return (0);
}
if (bytes != 4)
return (-1);