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[109.43.178.97]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4214186ccdcsm47515985e9.16.2024.06.04.07.40.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Jun 2024 07:40:21 -0700 (PDT) Message-ID: <49f8aadf-6e3f-4d2b-a32a-8ba941a3a2a1@redhat.com> Date: Tue, 4 Jun 2024 16:40:20 +0200 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH kvm-unit-tests] realmode: load above stack To: Paolo Bonzini , kvm@vger.kernel.org References: <20240604143507.1041901-1-pbonzini@redhat.com> Content-Language: en-US From: Thomas Huth Autocrypt: addr=thuth@redhat.com; keydata= xsFNBFH7eUwBEACzyOXKU+5Pcs6wNpKzrlJwzRl3VGZt95VCdb+FgoU9g11m7FWcOafrVRwU yYkTm9+7zBUc0sW5AuPGR/dp3pSLX/yFWsA/UB4nJsHqgDvDU7BImSeiTrnpMOTXb7Arw2a2 4CflIyFqjCpfDM4MuTmzTjXq4Uov1giGE9X6viNo1pxyEpd7PanlKNnf4PqEQp06X4IgUacW tSGj6Gcns1bCuHV8OPWLkf4hkRnu8hdL6i60Yxz4E6TqlrpxsfYwLXgEeswPHOA6Mn4Cso9O 0lewVYfFfsmokfAVMKWzOl1Sr0KGI5T9CpmRfAiSHpthhHWnECcJFwl72NTi6kUcUzG4se81 O6n9d/kTj7pzTmBdfwuOZ0YUSqcqs0W+l1NcASSYZQaDoD3/SLk+nqVeCBB4OnYOGhgmIHNW 0CwMRO/GK+20alxzk//V9GmIM2ACElbfF8+Uug3pqiHkVnKqM7W9/S1NH2qmxB6zMiJUHlTH gnVeZX0dgH27mzstcF786uPcdEqS0KJuxh2kk5IvUSL3Qn3ZgmgdxBMyCPciD/1cb7/Ahazr 3ThHQXSHXkH/aDXdfLsKVuwDzHLVSkdSnZdt5HHh75/NFHxwaTlydgfHmFFwodK8y/TjyiGZ zg2Kje38xnz8zKn9iesFBCcONXS7txENTzX0z80WKBhK+XSFJwARAQABzR5UaG9tYXMgSHV0 aCA8dGh1dGhAcmVkaGF0LmNvbT7CwXgEEwECACIFAlVgX6oCGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAAoJEC7Z13T+cC21EbIP/ii9cvT2HHGbFRl8HqGT6+7Wkb+XLMqJBMAIGiQK QIP3xk1HPTsLfVG0ao4hy/oYkGNOP8+ubLnZen6Yq3zAFiMhQ44lvgigDYJo3Ve59gfe99KX EbtB+X95ODARkq0McR6OAsPNJ7gpEUzfkQUUJTXRDQXfG/FX303Gvk+YU0spm2tsIKPl6AmV 1CegDljzjycyfJbk418MQmMu2T82kjrkEofUO2a24ed3VGC0/Uz//XCR2ZTo+vBoBUQl41BD eFFtoCSrzo3yPFS+w5fkH9NT8ChdpSlbNS32NhYQhJtr9zjWyFRf0Zk+T/1P7ECn6gTEkp5k ofFIA4MFBc/fXbaDRtBmPB0N9pqTFApIUI4vuFPPO0JDrII9dLwZ6lO9EKiwuVlvr1wwzsgq zJTPBU3qHaUO4d/8G+gD7AL/6T4zi8Jo/GmjBsnYaTzbm94lf0CjXjsOX3seMhaE6WAZOQQG tZHAO1kAPWpaxne+wtgMKthyPLNwelLf+xzGvrIKvLX6QuLoWMnWldu22z2ICVnLQChlR9d6 WW8QFEpo/FK7omuS8KvvopFcOOdlbFMM8Y/8vBgVMSsK6fsYUhruny/PahprPbYGiNIhKqz7 UvgyZVl4pBFjTaz/SbimTk210vIlkDyy1WuS8Zsn0htv4+jQPgo9rqFE4mipJjy/iboDzsFN BFH7eUwBEAC2nzfUeeI8dv0C4qrfCPze6NkryUflEut9WwHhfXCLjtvCjnoGqFelH/PE9NF4 4VPSCdvD1SSmFVzu6T9qWdcwMSaC+e7G/z0/AhBfqTeosAF5XvKQlAb9ZPkdDr7YN0a1XDfa +NgA+JZB4ROyBZFFAwNHT+HCnyzy0v9Sh3BgJJwfpXHH2l3LfncvV8rgFv0bvdr70U+On2XH 5bApOyW1WpIG5KPJlDdzcQTyptOJ1dnEHfwnABEfzI3dNf63rlxsGouX/NFRRRNqkdClQR3K gCwciaXfZ7ir7fF0u1N2UuLsWA8Ei1JrNypk+MRxhbvdQC4tyZCZ8mVDk+QOK6pyK2f4rMf/ WmqxNTtAVmNuZIwnJdjRMMSs4W4w6N/bRvpqtykSqx7VXcgqtv6eqoDZrNuhGbekQA0sAnCJ VPArerAZGArm63o39me/bRUQeQVSxEBmg66yshF9HkcUPGVeC4B0TPwz+HFcVhheo6hoJjLq knFOPLRj+0h+ZL+D0GenyqD3CyuyeTT5dGcNU9qT74bdSr20k/CklvI7S9yoQje8BeQAHtdV cvO8XCLrpGuw9SgOS7OP5oI26a0548M4KldAY+kqX6XVphEw3/6U1KTf7WxW5zYLTtadjISB X9xsRWSU+Yqs3C7oN5TIPSoj9tXMoxZkCIHWvnqGwZ7JhwARAQABwsFfBBgBAgAJBQJR+3lM AhsMAAoJEC7Z13T+cC21hPAQAIsBL9MdGpdEpvXs9CYrBkd6tS9mbaSWj6XBDfA1AEdQkBOn ZH1Qt7HJesk+qNSnLv6+jP4VwqK5AFMrKJ6IjE7jqgzGxtcZnvSjeDGPF1h2CKZQPpTw890k fy18AvgFHkVk2Oylyexw3aOBsXg6ukN44vIFqPoc+YSU0+0QIdYJp/XFsgWxnFIMYwDpxSHS 5fdDxUjsk3UBHZx+IhFjs2siVZi5wnHIqM7eK9abr2cK2weInTBwXwqVWjsXZ4tq5+jQrwDK cvxIcwXdUTLGxc4/Z/VRH1PZSvfQxdxMGmNTGaXVNfdFZjm4fz0mz+OUi6AHC4CZpwnsliGV ODqwX8Y1zic9viSTbKS01ZNp175POyWViUk9qisPZB7ypfSIVSEULrL347qY/hm9ahhqmn17 Ng255syASv3ehvX7iwWDfzXbA0/TVaqwa1YIkec+/8miicV0zMP9siRcYQkyTqSzaTFBBmqD oiT+z+/E59qj/EKfyce3sbC9XLjXv3mHMrq1tKX4G7IJGnS989E/fg6crv6NHae9Ckm7+lSs IQu4bBP2GxiRQ+NV3iV/KU3ebMRzqIC//DCOxzQNFNJAKldPe/bKZMCxEqtVoRkuJtNdp/5a yXFZ6TfE1hGKrDBYAm4vrnZ4CXFSBDllL59cFFOJCkn4Xboj/aVxxJxF30bn In-Reply-To: <20240604143507.1041901-1-pbonzini@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 04/06/2024 16.35, Paolo Bonzini wrote: > The bottom 32K of memory are generally reserved for use by the BIOS; > for example, traditionally the boot loader is placed at 0x7C00 and > the stack grows below that address. > > It turns out that with some versions of clang, realmode.flat has > become big enough that it overlaps the stack used by the multiboot > option ROM loader. The result is that a couple instructions are > overwritten. Typically one or two tests fail and that's it... > > Move the code above the forbidden region, in real 90s style. > > Reported-by: Thomas Huth > Signed-off-by: Paolo Bonzini > --- > x86/realmode.lds | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/x86/realmode.lds b/x86/realmode.lds > index 0ed3063b..e4782a98 100644 > --- a/x86/realmode.lds > +++ b/x86/realmode.lds > @@ -1,6 +1,6 @@ > SECTIONS > { > - . = 16K; > + . = 32K; > stext = .; > .text : { *(.init) *(.text) } > . = ALIGN(4K); This fails for me with: ld -m elf_i386 -nostdlib -o x86/realmode.elf \ -T /home/thuth/devel/kvm-unit-tests/x86/realmode.lds x86/realmode.o x86/realmode.o: in function `init_inregs': /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x79): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x82): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x8b): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x94): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0x9d): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xa6): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xaf): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xb8): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xc1): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:176:(.text+0xca): relocation truncated to fit: R_386_16 against `.bss' /home/thuth/devel/kvm-unit-tests/x86/realmode.c:180:(.text+0xda): additional relocation overflows omitted from the output make: *** [/home/thuth/devel/kvm-unit-tests/x86/Makefile.common:107: x86/realmode.elf] Error 1 Thomas