From: Ahmed Moneeb Azab <amazab@ncsu.edu>
To: xen-devel@lists.xensource.com
Subject: System Calls in x86_32
Date: Tue, 17 Jun 2008 18:56:53 -0400 [thread overview]
Message-ID: <48584135.9000301@ncsu.edu> (raw)
Hi All,
I need help understanding how the direct system calls work on the x86_32
architecture.
What I understand is that when a guest is initialized, it uses the
hypercall do_set_trap_table to initialize the trap table which calls
init_int80_direct_trap for system call interrupts. The later updates the
int80_desc structure in the VCPU of the guest so that the new address
gets the callback directly.
What I do not understand is where does the call back occur. Int80 is not
handles in the x86_32's entry.S?!!!! So, where is the code that issues
the callback?
Why is architecture is different on x86_64. The entry.S contains an
entry for int80. Does this affect the performance of the guests?
Ahmed
next reply other threads:[~2008-06-17 22:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-17 22:56 Ahmed Moneeb Azab [this message]
2008-06-19 13:42 ` System Calls in x86_32 Grzegorz Miłoś
2008-06-19 14:42 ` Jan Beulich
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