Commits on Sep 18, 2024

1. x86 bootloader: keep 8259 PIC enabled when reading from disk …

   Following a recent update of the hypervisor and/or the BIOS
   firmware on AWS Xen-based instances (e.g. t2 instances), the BIOS
   never returns from the INT 13H routine that the stage1 bootloader
   uses to read stage2 code from disk. This prevents the kernel from
   booting on those instance types.
   This change fixes the above issue by disabling the 8259 PIC only
   after reading stage2 code from disk. This allows the BIOS firmware
   to work properly when executing the INT 13H routine, and also
   allows this routine to be executed more than once. Therefore, the
   limitation of 64 kB on stage2 code size is being lifted, since a
   larger stage2 binary (which requires more than one INT 13H call in
   order to be read from disk) is now properly handled on AWS
   instances.

   

   francescolavra committed Sep 18, 2024
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